International Journal of Refractory Metals & Hard Materials最新文献_第7页

Formation of property gradient in coarse-grained niobium using a wedge tool: Experiment and analysis 使用楔形工具在粗粒铌中形成性质梯度：实验与分析

IF 4.2 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Refractory Metals & Hard Materials

Pub Date : 2024-09-27 DOI: 10.1016/j.ijrmhm.2024.106905

Oleksandr Tarasov , Jakob Kübarsepp , Mart Viljus , Mart Saarna , Fjodor Sergejev

We introduce a novel severe plastic deformation process for coarse-grained niobium, which employs a tool with an inclined (wedge) surface for deforming the material by a reverse shear scheme. The process increases the intensity of shear deformations and the depth of plastic deformation in the body of the workpiece when a wedge tool acts on its surface. The essence of the process is in the repeated displacement of the workpiece material in opposite directions during the asymmetrical introduction of a wedge tool until the required degree of deformation is accumulated in the tool-affected volume. This deformation scheme applies a 15° angle wedge tool to a 21-mm high workpiece. After nine cycles of plastic deformation, a gradient of the accumulated degree of deformation in the range of true strain e = 0.3–4.5 was created. At maximum deformation, the microhardness of the workpieces increased by 1.86 times and the tensile strength by 1.6 times. Fractograms show a significant influence of the accumulated degree of deformation on the nature of the fracture. The finite element method simulation of the deformation process showed that creating a uniformly strengthened layer requires at least five deforming operations. For example, the proposed reverse shear process with a wedge tool can be applied to improve the structure of the surface layers of niobium ingots for subsequent forming. Due to the creation of a significant gradient of properties, the reverse shear process can be used as an express method for determining the mechanical characteristics of different materials in a wide range of accumulated degree of deformation.

我们为粗粒铌引入了一种新型的严重塑性变形工艺，该工艺采用带有倾斜（楔形）表面的工具，通过反向剪切方案使材料变形。当楔形工具作用于工件表面时，该工艺可增加剪切变形强度和工件主体的塑性变形深度。该工艺的精髓在于，在不对称引入楔形工具时，工件材料向相反方向反复位移，直到工具影响体积内累积到所需的变形程度。该变形方案在 21 毫米高的工件上使用 15° 角的楔形工具。经过九次塑性变形后，在真实应变 e = 0.3-4.5 范围内形成了累积变形度梯度。在最大变形时，工件的显微硬度增加了 1.86 倍，抗拉强度增加了 1.6 倍。断口图显示，累积变形程度对断口性质有显著影响。对变形过程的有限元法模拟表明，形成均匀强化层至少需要五次变形操作。例如，建议使用楔形工具的反向剪切工艺可用于改善铌锭表层的结构，以便后续成形。由于反向剪切工艺可产生明显的性能梯度，因此可作为一种明确的方法，用于确定不同材料在广泛的累积变形程度下的机械特性。

{"title":"Formation of property gradient in coarse-grained niobium using a wedge tool: Experiment and analysis","authors":"Oleksandr Tarasov , Jakob Kübarsepp , Mart Viljus , Mart Saarna , Fjodor Sergejev","doi":"10.1016/j.ijrmhm.2024.106905","DOIUrl":"10.1016/j.ijrmhm.2024.106905","url":null,"abstract":"<div><div>We introduce a novel severe plastic deformation process for coarse-grained niobium, which employs a tool with an inclined (wedge) surface for deforming the material by a reverse shear scheme. The process increases the intensity of shear deformations and the depth of plastic deformation in the body of the workpiece when a wedge tool acts on its surface. The essence of the process is in the repeated displacement of the workpiece material in opposite directions during the asymmetrical introduction of a wedge tool until the required degree of deformation is accumulated in the tool-affected volume. This deformation scheme applies a 15° angle wedge tool to a 21-mm high workpiece. After nine cycles of plastic deformation, a gradient of the accumulated degree of deformation in the range of true strain <em>e</em> = 0.3–4.5 was created. At maximum deformation, the microhardness of the workpieces increased by 1.86 times and the tensile strength by 1.6 times. Fractograms show a significant influence of the accumulated degree of deformation on the nature of the fracture. The finite element method simulation of the deformation process showed that creating a uniformly strengthened layer requires at least five deforming operations. For example, the proposed reverse shear process with a wedge tool can be applied to improve the structure of the surface layers of niobium ingots for subsequent forming. Due to the creation of a significant gradient of properties, the reverse shear process can be used as an express method for determining the mechanical characteristics of different materials in a wide range of accumulated degree of deformation.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"125 ","pages":"Article 106905"},"PeriodicalIF":4.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The microstructure evolution, wear and corrosion behavior of biomedical Ti40Zr40Nb5Ta12Sn3 MEA at different heat treatment conditions 不同热处理条件下生物医学 Ti40Zr40Nb5Ta12Sn3 MEA 的微观结构演变、磨损和腐蚀行为

IF 4.2 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Refractory Metals & Hard Materials

Pub Date : 2024-09-27 DOI: 10.1016/j.ijrmhm.2024.106906

Dandan Zhu , Shiwen Hu , Xiaoqiang Li , Ping Long , Youtong Yang , Qinglin Li , Dexue Liu

In the present study, the microstructure, wear and corrosion properties of a novel Ti₄₀Zr₄₀Nb₅Ta₁₂Sn₃ medium-entropy alloy (MEA) processed by warm rolling and subsequent heat treatment were investigated. The findings reveal nanoscale α” phase precipitated in the alloy following annealing at temperatures of 450 °C, 550 °C, and 650 °C. During the friction and wear of the MEA, it was observed that the wet friction coefficient and wear rate of the alloy surpassed those under dry friction conditions. The wear mechanisms of alloys were abrasive wear and oxidation wear during dry friction, and abrasive wear and corrosion wear during wet friction. Furthermore, Sn₃–450 alloy exhibited exceptional corrosion resistance compared to Ti6Al4V alloy, with a lower corrosion current density (I_corr: 0.165 μA·cm⁻²) and a higher corrosion potential (E_corr: −0.638 ± 0.015 V) in phosphate buffered saline (PBS) solution. These results suggest the significant potential application of the Sn₃–450 alloy in biomedical applications.

本研究调查了一种新型 Ti40Zr40Nb5Ta12Sn3 中熵合金（MEA）的微观结构、磨损和腐蚀特性，该合金是通过热轧和后续热处理加工而成的。研究结果表明，在 450 ℃、550 ℃ 和 650 ℃ 的退火温度下，合金中析出了纳米级 α "相。在 MEA 的摩擦和磨损过程中，观察到合金的湿摩擦系数和磨损率超过了干摩擦条件下的磨损率。合金的磨损机制为干摩擦时的磨料磨损和氧化磨损，以及湿摩擦时的磨料磨损和腐蚀磨损。此外，与 Ti6Al4V 合金相比，Sn3-450 合金表现出优异的耐腐蚀性，在磷酸盐缓冲盐水（PBS）溶液中具有更低的腐蚀电流密度（Icorr：0.165 μA-cm-2）和更高的腐蚀电位（Ecorr：-0.638 ± 0.015 V）。这些结果表明，Sn3-450 合金在生物医学应用中具有巨大的应用潜力。

{"title":"The microstructure evolution, wear and corrosion behavior of biomedical Ti40Zr40Nb5Ta12Sn3 MEA at different heat treatment conditions","authors":"Dandan Zhu , Shiwen Hu , Xiaoqiang Li , Ping Long , Youtong Yang , Qinglin Li , Dexue Liu","doi":"10.1016/j.ijrmhm.2024.106906","DOIUrl":"10.1016/j.ijrmhm.2024.106906","url":null,"abstract":"<div><div>In the present study, the microstructure, wear and corrosion properties of a novel Ti<sub>40</sub>Zr<sub>40</sub>Nb<sub>5</sub>Ta<sub>12</sub>Sn<sub>3</sub> medium-entropy alloy (MEA) processed by warm rolling and subsequent heat treatment were investigated. The findings reveal nanoscale α” phase precipitated in the alloy following annealing at temperatures of 450 °C, 550 °C, and 650 °C. During the friction and wear of the MEA, it was observed that the wet friction coefficient and wear rate of the alloy surpassed those under dry friction conditions. The wear mechanisms of alloys were abrasive wear and oxidation wear during dry friction, and abrasive wear and corrosion wear during wet friction. Furthermore, Sn<sub>3</sub>–450 alloy exhibited exceptional corrosion resistance compared to Ti6Al4V alloy, with a lower corrosion current density (I<sub>corr</sub>: 0.165 μA·cm<sup>−2</sup>) and a higher corrosion potential (E<sub>corr</sub>: −0.638 ± 0.015 V) in phosphate buffered saline (PBS) solution. These results suggest the significant potential application of the Sn<sub>3</sub>–450 alloy in biomedical applications.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"125 ","pages":"Article 106906"},"PeriodicalIF":4.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142330054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Study on the effect of multi-walled carbon nanotube (MWCNT) addition on the microstructure, mechanical and cutting performance of silicon nitride ceramic tools 研究添加多壁碳纳米管 (MWCNT) 对氮化硅陶瓷工具微观结构、机械和切削性能的影响

IF 4.2 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Refractory Metals & Hard Materials

Pub Date : 2024-09-27 DOI: 10.1016/j.ijrmhm.2024.106907

Lei Huang, Yingxu Dong, Zhenhua Wang, Dongying Zhang, Zuorong Yu

Silicon nitride (Si₃N₄) ceramics incorporated with 0–1.5 wt% multi-walled carbon nanotubes (MWCNTs) were synthesised by the spark plasma sintering technology. The effects of the low-content MWCNT addition on the microstructure, density, mechanical properties and cutting performance against nickel-based superalloys (Inconel 718) of the Si₃N₄/MWCNTs ceramic tools were investigated by the X-ray diffraction, field emission scanning electron microscope, Vickers hardness tester, universal tester, ball-on-disk reciprocating tester and cutting experiment. The results showed that the incorporation of MWCNTs enhanced the conversion rate of Si₃N₄ structure from the polar α form to the polar β form and reduced the friction coefficient of the composite. However, due to the agglomeration of MWCNTs, the hardness and fracture toughness of the Si₃N₄/MWCNTs ceramics were observed to decrease by 5.03 % and 13.97 %, respectively, compared to pure Si₃N₄ ceramics. A higher addition rate of the MWCNT would further accelerate tool wear and significantly diminish tool life. The predominant wear mechanism of the Si₃N₄/MWCNTs ceramic tools when milling Inconel 718 was groove-shape wear and adhesive wear.

采用火花等离子烧结技术合成了含有 0-1.5 wt% 多壁碳纳米管 (MWCNT) 的氮化硅 (Si3N4) 陶瓷。通过 X 射线衍射、场发射扫描电子显微镜、维氏硬度计、万能试验机、盘上球往复试验机和切削实验，研究了低含量 MWCNT 的添加对 Si3N4/MWCNTs 陶瓷工具的微观结构、密度、机械性能和与镍基超级合金（Inconel 718）的切削性能的影响。结果表明，MWCNTs 的加入提高了 Si3N4 结构从极性 α 形式向极性 β 形式的转化率，降低了复合材料的摩擦系数。然而，由于 MWCNTs 的聚集，与纯 Si3N4 陶瓷相比，Si3N4/MWCNTs 陶瓷的硬度和断裂韧性分别降低了 5.03 % 和 13.97 %。更高的 MWCNT 添加率会进一步加速工具磨损，显著降低工具寿命。在铣削 Inconel 718 时，Si3N4/MWCNTs 陶瓷工具的主要磨损机制是槽形磨损和粘着磨损。

{"title":"Study on the effect of multi-walled carbon nanotube (MWCNT) addition on the microstructure, mechanical and cutting performance of silicon nitride ceramic tools","authors":"Lei Huang, Yingxu Dong, Zhenhua Wang, Dongying Zhang, Zuorong Yu","doi":"10.1016/j.ijrmhm.2024.106907","DOIUrl":"10.1016/j.ijrmhm.2024.106907","url":null,"abstract":"<div><div>Silicon nitride (Si<sub>3</sub>N<sub>4</sub>) ceramics incorporated with 0–1.5 wt% multi-walled carbon nanotubes (MWCNTs) were synthesised by the spark plasma sintering technology. The effects of the low-content MWCNT addition on the microstructure, density, mechanical properties and cutting performance against nickel-based superalloys (Inconel 718) of the Si<sub>3</sub>N<sub>4</sub>/MWCNTs ceramic tools were investigated by the X-ray diffraction, field emission scanning electron microscope, Vickers hardness tester, universal tester, ball-on-disk reciprocating tester and cutting experiment. The results showed that the incorporation of MWCNTs enhanced the conversion rate of Si<sub>3</sub>N<sub>4</sub> structure from the polar α form to the polar β form and reduced the friction coefficient of the composite. However, due to the agglomeration of MWCNTs, the hardness and fracture toughness of the Si<sub>3</sub>N<sub>4</sub>/MWCNTs ceramics were observed to decrease by 5.03 % and 13.97 %, respectively, compared to pure Si<sub>3</sub>N<sub>4</sub> ceramics. A higher addition rate of the MWCNT would further accelerate tool wear and significantly diminish tool life. The predominant wear mechanism of the Si<sub>3</sub>N<sub>4</sub>/MWCNTs ceramic tools when milling Inconel 718 was groove-shape wear and adhesive wear.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"125 ","pages":"Article 106907"},"PeriodicalIF":4.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142330212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental study on tribological behavior of a binderless cemented carbide at high contact stress 高接触应力下无粘结剂硬质合金摩擦学行为的实验研究

IF 4.2 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Refractory Metals & Hard Materials

Pub Date : 2024-09-26 DOI: 10.1016/j.ijrmhm.2024.106901

Qingde Su

Knowledge of frictional evolution and associated damage mechanism during sliding wear conditions using binderless WC-based cemented carbide is lacking. In this study, the frictional evolution and corresponding transformation of microstructure, and wear mechanisms of Al₂O₃/WC-based cemented carbide due to the effect of different contact pressure, especially high pressure have been explored using a reciprocating ball-on-flat sliding wear tester, which was experimentally simulated following the ASTM G133–02 standard. The dynamic curves in friction coefficient with the sliding time were described. The microscopic 3D topography of contact surface was obtained by the MFP-3D atomic force microscope. The material removal and the wear rate were discussed. Worn surface morphologies at different moments, cross-sectional images of wear tracks at different loads, and wear debris were taken by field emission scanning electron microscope. The results suggested that the pressure plays a decisive role in frictional evolution and wear characteristics. Two models of frictional evolution were declared. A novel “surge” phenomena in friction coefficient was found and explained at high contact pressure. Wear transition from mild wear to severe wear was confirmed. More than one wear mechanism was observed, including micro-cutting (polishing), generation and propagation of cracks, cracking-induced spalling, plastic deformation, and the formation of tribolayer.

关于使用无粘结剂的 WC 基硬质合金在滑动磨损条件下的摩擦演化和相关损伤机制的知识还很缺乏。本研究使用往复式球对平滑动磨损试验机，按照 ASTM G133-02 标准进行实验模拟，探讨了不同接触压力（尤其是高压）作用下 Al2O3/WC 基硬质合金的摩擦演化和相应的微观结构变化以及磨损机理。研究描述了摩擦系数随滑动时间变化的动态曲线。通过 MFP-3D 原子力显微镜获得了接触表面的微观三维形貌。讨论了材料去除率和磨损率。用场发射扫描电子显微镜拍摄了不同时刻的磨损表面形态、不同载荷下磨损轨迹的截面图像以及磨损碎屑。结果表明，压力在摩擦演变和磨损特性中起着决定性作用。研究宣布了两种摩擦演变模型。发现并解释了高接触压力下摩擦系数的新 "激增 "现象。确认了从轻度磨损到严重磨损的磨损过渡。观察到不止一种磨损机制，包括微切削（抛光）、裂纹的产生和扩展、裂纹引起的剥落、塑性变形和摩擦层的形成。

{"title":"Experimental study on tribological behavior of a binderless cemented carbide at high contact stress","authors":"Qingde Su","doi":"10.1016/j.ijrmhm.2024.106901","DOIUrl":"10.1016/j.ijrmhm.2024.106901","url":null,"abstract":"<div><div>Knowledge of frictional evolution and associated damage mechanism during sliding wear conditions using binderless WC-based cemented carbide is lacking. In this study, the frictional evolution and corresponding transformation of microstructure, and wear mechanisms of Al<sub>2</sub>O<sub>3</sub>/WC-based cemented carbide due to the effect of different contact pressure, especially high pressure have been explored using a reciprocating ball-on-flat sliding wear tester, which was experimentally simulated following the ASTM <span><span>G133</span><svg><path></path></svg></span>–02 standard. The dynamic curves in friction coefficient with the sliding time were described. The microscopic 3D topography of contact surface was obtained by the MFP-3D atomic force microscope. The material removal and the wear rate were discussed. Worn surface morphologies at different moments, cross-sectional images of wear tracks at different loads, and wear debris were taken by field emission scanning electron microscope. The results suggested that the pressure plays a decisive role in frictional evolution and wear characteristics. Two models of frictional evolution were declared. A novel “surge” phenomena in friction coefficient was found and explained at high contact pressure. Wear transition from mild wear to severe wear was confirmed. More than one wear mechanism was observed, including micro-cutting (polishing), generation and propagation of cracks, cracking-induced spalling, plastic deformation, and the formation of tribolayer.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"125 ","pages":"Article 106901"},"PeriodicalIF":4.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142330214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Enhanced wear resistance and strength synergy in Ti3AlC2 MAX through in-situ synthesis of nano TiB2 heterostructure 通过原位合成纳米 TiB2 异质结构增强 Ti3AlC2 MAX 的耐磨性和强度协同作用

IF 4.2 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Refractory Metals & Hard Materials

Pub Date : 2024-09-26 DOI: 10.1016/j.ijrmhm.2024.106904

Dongting Li , Chang Liu , Ying Liu , Liyu Zhou , Kaiqiang Wang , Lu Wang , Renquan Wang

The rapid development of science and technology poses the core parts and techniques of industrial tribo-systems facing more stringent situations like high temperature exceeding 600 °C. For this case, solid lubrication materials are required to possess high strength, low friction coefficient and high wear resistance over a wide temperature range. However, achieving such “strong wearable yet lubricated” materials have proven challenging. Here we report a unique reinforced strategy for lubricated Ti₃AlC₂ MAX ceramic by in-situ synthesis of nano TiB₂ heterostructure, which results in a superior high temperature strength and lubrication simultaneously excess other traditional solid-lubrication materials. Such TiB₂/Ti₃AlC₂ composite employs a high level of compressive strength (1120 MPa ∼ 1368 MPa), wear resistance (<10^‐⁵ mm³/(N∙m)) and low friction coefficient (<0.4) at even 800 °C. We show that its unusual properties stem from the introduction of TiB₂ nanocrystalline densified and strengthened the Ti₃AlC₂ matrix thus to ensure the high strength. Meanwhile, the TiB₂ also undergoes rapid oxidation along high temperatures friction, resulting in the formation of a continuous and smooth lubricative tribofilm containing solid lubricant B₂O₃, leading to exceptional solid lubrication effect at high temperature. Our finding provides a potential material portfolio and a new design strategy for high temperature solid-lubricative applications.

随着科学技术的飞速发展，工业摩擦系统的核心部件和技术面临着更严格的要求，如超过 600 °C 的高温。在这种情况下，要求固体润滑材料在宽温度范围内具有高强度、低摩擦系数和高耐磨性。然而，实现这种 "高强度耐磨润滑 "材料已被证明具有挑战性。在此，我们报告了一种独特的润滑 Ti3AlC2 MAX 陶瓷强化策略，即通过原位合成纳米 TiB2 异质结构，同时获得优于其他传统固体润滑材料的高温强度和润滑性能。这种 TiB2/Ti3AlC2 复合材料在 800 ℃ 下仍具有很高的抗压强度（1120 MPa ∼ 1368 MPa）、耐磨性（<10-5 mm3/(N∙m)）和低摩擦系数（<0.4）。我们的研究表明，TiB2 纳米晶的引入使 Ti3AlC2 基体致密化并得到强化，从而确保了其高强度，这是其不同寻常的特性的源泉。同时，TiB2 还会在高温摩擦过程中发生快速氧化，形成含有固体润滑剂 B2O3 的连续光滑的润滑三膜，从而在高温下产生优异的固体润滑效果。我们的发现为高温固体润滑应用提供了潜在的材料组合和新的设计策略。

{"title":"Enhanced wear resistance and strength synergy in Ti3AlC2 MAX through in-situ synthesis of nano TiB2 heterostructure","authors":"Dongting Li , Chang Liu , Ying Liu , Liyu Zhou , Kaiqiang Wang , Lu Wang , Renquan Wang","doi":"10.1016/j.ijrmhm.2024.106904","DOIUrl":"10.1016/j.ijrmhm.2024.106904","url":null,"abstract":"<div><div>The rapid development of science and technology poses the core parts and techniques of industrial tribo-systems facing more stringent situations like high temperature exceeding 600 °C. For this case, solid lubrication materials are required to possess high strength, low friction coefficient and high wear resistance over a wide temperature range. However, achieving such “strong wearable yet lubricated” materials have proven challenging. Here we report a unique reinforced strategy for lubricated Ti<sub>3</sub>AlC<sub>2</sub> MAX ceramic by in-situ synthesis of nano TiB<sub>2</sub> heterostructure, which results in a superior high temperature strength and lubrication simultaneously excess other traditional solid-lubrication materials. Such TiB<sub>2</sub>/Ti<sub>3</sub>AlC<sub>2</sub> composite employs a high level of compressive strength (1120 MPa ∼ 1368 MPa), wear resistance (<10<sup>‐</sup><sup>5</sup> mm<sup>3</sup>/(N∙m)) and low friction coefficient (<0.4) at even 800 °C. We show that its unusual properties stem from the introduction of TiB<sub>2</sub> nanocrystalline densified and strengthened the Ti<sub>3</sub>AlC<sub>2</sub> matrix thus to ensure the high strength. Meanwhile, the TiB<sub>2</sub> also undergoes rapid oxidation along high temperatures friction, resulting in the formation of a continuous and smooth lubricative tribofilm containing solid lubricant B<sub>2</sub>O<sub>3</sub>, leading to exceptional solid lubrication effect at high temperature. Our finding provides a potential material portfolio and a new design strategy for high temperature solid-lubricative applications.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"125 ","pages":"Article 106904"},"PeriodicalIF":4.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142330055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Behavior of boron and nitrogen impurities in diamonds synthesized at high pressure and high temperature 高压高温合成金刚石中的硼和氮杂质的行为

IF 4.2 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Refractory Metals & Hard Materials

Pub Date : 2024-09-24 DOI: 10.1016/j.ijrmhm.2024.106902

Zhiwen Wang , Ziqi Wang , Hongyu Zhao , Bowei Li , Qianyu Guo , Aokai Xu , Shengxue Wang , Hongan Ma , Liangchao Chen , Xiaopeng Jia

The effect of nitrogen on the growth of boron-doped diamonds was investigated by removing or adding nitrogen impurities. Optical microscopy images showed that adding a small amount of boron to nitrogen-free diamond completely transformed the diamond into an opaque black color. In the presence of small amounts of boron, the addition of nitrogen diminished the chromogenic properties of boron impurities in diamond. The FTIR spectra showed a compensatory interaction between boron and nitrogen in diamond, causing a portion of the nitrogen to exist as N⁺ center. Raman spectroscopy confirmed that adding small amounts of nitrogen to diamond reduced the stresses in the diamond and improved its quality, whereas adding excessive amounts of nitrogen reduced the quality. The Hall effect measurements showed that adding nitrogen to boron-doped diamond reduced its p-conductivity, causing an increase in its resistivity and a decrease in its carrier concentration.

通过去除或添加氮杂质，研究了氮对掺硼金刚石生长的影响。光学显微镜图像显示，在无氮金刚石中加入少量硼会使金刚石完全变成不透明的黑色。在存在少量硼的情况下，氮的加入会降低金刚石中硼杂质的致色性。傅立叶变换红外光谱显示，金刚石中的硼和氮之间存在补偿作用，导致部分氮以 N+ 中心的形式存在。拉曼光谱证实，在金刚石中添加少量的氮可以减少金刚石中的应力，提高其质量，而添加过量的氮则会降低质量。霍尔效应测量结果表明，在掺硼金刚石中加入氮元素会降低其对导电率，从而导致其电阻率增加，载流子浓度降低。

{"title":"Behavior of boron and nitrogen impurities in diamonds synthesized at high pressure and high temperature","authors":"Zhiwen Wang , Ziqi Wang , Hongyu Zhao , Bowei Li , Qianyu Guo , Aokai Xu , Shengxue Wang , Hongan Ma , Liangchao Chen , Xiaopeng Jia","doi":"10.1016/j.ijrmhm.2024.106902","DOIUrl":"10.1016/j.ijrmhm.2024.106902","url":null,"abstract":"<div><div>The effect of nitrogen on the growth of boron-doped diamonds was investigated by removing or adding nitrogen impurities. Optical microscopy images showed that adding a small amount of boron to nitrogen-free diamond completely transformed the diamond into an opaque black color. In the presence of small amounts of boron, the addition of nitrogen diminished the chromogenic properties of boron impurities in diamond. The FTIR spectra showed a compensatory interaction between boron and nitrogen in diamond, causing a portion of the nitrogen to exist as N<sup>+</sup> center. Raman spectroscopy confirmed that adding small amounts of nitrogen to diamond reduced the stresses in the diamond and improved its quality, whereas adding excessive amounts of nitrogen reduced the quality. The Hall effect measurements showed that adding nitrogen to boron-doped diamond reduced its p-conductivity, causing an increase in its resistivity and a decrease in its carrier concentration.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"125 ","pages":"Article 106902"},"PeriodicalIF":4.2,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effect of annealing temperature on the microstructure and mechanical properties of Al0.2CrNbTiV lightweight refractory high-entropy alloy 退火温度对 Al0.2CrNbTiV 轻质高熵难熔合金微观结构和力学性能的影响

IF 4.2 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Refractory Metals & Hard Materials

Pub Date : 2024-09-24 DOI: 10.1016/j.ijrmhm.2024.106903

Liyan Lou , Tianhui Chen , Zhijiang Bi , Wei Wang , Zhihai Cai , Ji Zhou , Ruohui Shuai , Yi Liu , Haidou Wang , Chengxin Li

The DSC analysis and heat treatment of the newly proposed Al_0.2CrNbTiV lightweight refractory high-entropy alloy prepared by vacuum arc melting was investigated, and the evolutions of the microstructure and mechanical properties of the alloy after homogenization annealing at 650 °C, 850 °C and 1050 °C for 12 h were analyzed. The results show that the Al_0.2CrNbTiV high-entropy alloy could maintain stable BCC solid solution structure from room temperature to 800 °C. The alloy annealed at 650 °C exhibited simple BCC structure with coarse equiaxed grains; after annealing at 850 °C, fine acicular and irregular block-like C14 Laves phases were uniformly precipitated in the grain and grain boundaries, meanwhile, the C14 Laves phase get coarser with the annealing temperature increased to 1050 °C. With the increase of annealing temperature, the microhardness of the Al_0.2CrNbTiV alloy increased first and then decreased, reaching the maximum value of 692 HV after annealing at 850 °C. Due to the high dislocation density and the formation of kink bands, the alloy annealed at 650 °C showed a good combination of plastic and strength, with the work hardening ability strengthened simultaneously, the compressive yield strength could be up to 1454 MPa, with strain >50 %. Due to the precipitation of the hard and brittle C14 Laves phase, the load-bearing capacity of the alloy was reduced after annealing at 850 °C and 1050 °C. However, the wear resistance of the alloy also improved with the presence of the hard phase. The friction coefficient of Al_0.2CrNbTiV alloy annealed at 650 °C is 0.67, with the abrasive wear acting as the main wear mechanism, and the alloy after annealing at 850 °C shew the best wear resistance, with the friction coefficient of 0.63, and delamination wear mechanism.

研究了采用真空电弧熔炼法制备的新型 Al0.2CrNbTiV 轻质高熵难熔合金的 DSC 分析和热处理，分析了合金在 650 ℃、850 ℃ 和 1050 ℃ 下均匀化退火 12 h 后的微观组织和力学性能变化。结果表明，Al0.2CrNbTiV 高熵合金从室温到 800 ℃ 都能保持稳定的 BCC 固溶体结构。650 ℃退火的合金呈现简单的 BCC 结构，晶粒粗大等轴；850 ℃退火后，晶粒和晶界中均匀析出细小的针状和不规则块状 C14 Laves 相，同时随着退火温度升高至 1050 ℃，C14 Laves 相变得更加粗大。随着退火温度的升高，Al0.2CrNbTiV 合金的显微硬度先升高后降低，在 850 ℃ 退火后达到最大值 692 HV。由于高位错密度和扭结带的形成，650 ℃退火的合金显示出良好的塑性和强度结合，加工硬化能力同时得到加强，抗压屈服强度可达 1454 MPa，应变为 50%。由于析出了硬脆的 C14 Laves 相，在 850 ℃ 和 1050 ℃ 退火后，合金的承载能力有所下降。然而，合金的耐磨性也随着硬相的存在而提高。在 650 ℃ 退火的 Al0.2CrNbTiV 合金的摩擦系数为 0.67，主要磨损机制为磨料磨损，而在 850 ℃ 退火后的合金耐磨性最好，摩擦系数为 0.63，磨损机制为分层磨损。

{"title":"Effect of annealing temperature on the microstructure and mechanical properties of Al0.2CrNbTiV lightweight refractory high-entropy alloy","authors":"Liyan Lou , Tianhui Chen , Zhijiang Bi , Wei Wang , Zhihai Cai , Ji Zhou , Ruohui Shuai , Yi Liu , Haidou Wang , Chengxin Li","doi":"10.1016/j.ijrmhm.2024.106903","DOIUrl":"10.1016/j.ijrmhm.2024.106903","url":null,"abstract":"<div><div>The DSC analysis and heat treatment of the newly proposed Al<sub>0.2</sub>CrNbTiV lightweight refractory high-entropy alloy prepared by vacuum arc melting was investigated, and the evolutions of the microstructure and mechanical properties of the alloy after homogenization annealing at 650 °C, 850 °C and 1050 °C for 12 h were analyzed. The results show that the Al<sub>0.2</sub>CrNbTiV high-entropy alloy could maintain stable BCC solid solution structure from room temperature to 800 °C. The alloy annealed at 650 °C exhibited simple BCC structure with coarse equiaxed grains; after annealing at 850 °C, fine acicular and irregular block-like C14 Laves phases were uniformly precipitated in the grain and grain boundaries, meanwhile, the C14 Laves phase get coarser with the annealing temperature increased to 1050 °C. With the increase of annealing temperature, the microhardness of the Al<sub>0.2</sub>CrNbTiV alloy increased first and then decreased, reaching the maximum value of 692 HV after annealing at 850 °C. Due to the high dislocation density and the formation of kink bands, the alloy annealed at 650 °C showed a good combination of plastic and strength, with the work hardening ability strengthened simultaneously, the compressive yield strength could be up to 1454 MPa, with strain >50 %. Due to the precipitation of the hard and brittle C14 Laves phase, the load-bearing capacity of the alloy was reduced after annealing at 850 °C and 1050 °C. However, the wear resistance of the alloy also improved with the presence of the hard phase. The friction coefficient of Al<sub>0.2</sub>CrNbTiV alloy annealed at 650 °C is 0.67, with the abrasive wear acting as the main wear mechanism, and the alloy after annealing at 850 °C shew the best wear resistance, with the friction coefficient of 0.63, and delamination wear mechanism.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"125 ","pages":"Article 106903"},"PeriodicalIF":4.2,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142327210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Strengthening mechanisms and research progress in the W/Cu interfaces 加强 W/Cu 界面的机制和研究进展

IF 4.2 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Refractory Metals & Hard Materials

Pub Date : 2024-09-24 DOI: 10.1016/j.ijrmhm.2024.106900

Lai-Ma Luo , Xi-Peng Ding , Wang-Zhi Xu , Cai-Yan Wang , Yong-Qiang Qin , Yu-Cheng Wu

Tungsten‑copper (WCu) composites integrate the high melting point, strength, and superior wear and arc resistance of tungsten with the exceptional electrical and thermal conductivity and good plasticity of copper. This combination makes them ideal for applications requiring high thermal conductivity and resistance to high temperatures. However, producing high-quality composites is challenging due to the significant differences in crystal structure and physical properties between tungsten and copper. Under high temperature load conditions, the WCu interface is subjected to substantial thermal stresses, which can lead to crack formation and eventual material failure. This review systematically analyzes methods to enhance the bonding strength of the W/Cu interface, suppress crack initiation and propagation, and mitigate interface thermal stresses. The focus is on physical bonding, chemical bonding, and the design and preparation of WCu functionally graded materials (FGMs). The mechanisms for strengthening the W/Cu interface are elucidated. Additionally, this review addresses the effects of grain refinement and work hardening at the interface on the microstructure and overall properties of WCu composites. Finally, the review summarizes the prospects for W/Cu interface research and highlights the challenges for future investigations.

钨-铜（WCu）复合材料将钨的高熔点、高强度、优异的耐磨性和耐电弧性与铜的优异导电性、导热性和良好的可塑性融为一体。这种组合使其非常适合需要高导热性和耐高温的应用。然而，由于钨和铜在晶体结构和物理性能方面存在显著差异，生产高质量的复合材料具有挑战性。在高温负载条件下，钨铜界面会承受巨大的热应力，从而导致裂纹的形成和材料的最终失效。本综述系统分析了增强钨/铜界面结合强度、抑制裂纹产生和扩展以及减轻界面热应力的方法。重点是物理键合、化学键合以及 WCu 功能分级材料 (FGM) 的设计和制备。本综述阐明了强化 W/Cu 界面的机制。此外，本综述还探讨了晶粒细化和界面加工硬化对 WCu 复合材料微观结构和整体性能的影响。最后，综述总结了 W/Cu 界面研究的前景，并强调了未来研究面临的挑战。

{"title":"Strengthening mechanisms and research progress in the W/Cu interfaces","authors":"Lai-Ma Luo , Xi-Peng Ding , Wang-Zhi Xu , Cai-Yan Wang , Yong-Qiang Qin , Yu-Cheng Wu","doi":"10.1016/j.ijrmhm.2024.106900","DOIUrl":"10.1016/j.ijrmhm.2024.106900","url":null,"abstract":"<div><div>Tungsten‑copper (W<img>Cu) composites integrate the high melting point, strength, and superior wear and arc resistance of tungsten with the exceptional electrical and thermal conductivity and good plasticity of copper. This combination makes them ideal for applications requiring high thermal conductivity and resistance to high temperatures. However, producing high-quality composites is challenging due to the significant differences in crystal structure and physical properties between tungsten and copper. Under high temperature load conditions, the W<img>Cu interface is subjected to substantial thermal stresses, which can lead to crack formation and eventual material failure. This review systematically analyzes methods to enhance the bonding strength of the W/Cu interface, suppress crack initiation and propagation, and mitigate interface thermal stresses. The focus is on physical bonding, chemical bonding, and the design and preparation of W<img>Cu functionally graded materials (FGMs). The mechanisms for strengthening the W/Cu interface are elucidated. Additionally, this review addresses the effects of grain refinement and work hardening at the interface on the microstructure and overall properties of W<img>Cu composites. Finally, the review summarizes the prospects for W/Cu interface research and highlights the challenges for future investigations.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"125 ","pages":"Article 106900"},"PeriodicalIF":4.2,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Powder rheology and characterization of new and zinc recycled WC-6wt%Co powders 新型和锌再生 WC-6wt%Co 粉末的流变性和表征

IF 4.2 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Refractory Metals & Hard Materials

Pub Date : 2024-09-23 DOI: 10.1016/j.ijrmhm.2024.106889

C.S. Freemantle , N. Sacks

Four industrially manufactured WC-6wt%Co powders were studied in terms of bulk properties, morphology and powder rheology. Two powders, comprising 100 % fresh raw material, a 100 % zinc recycled powder and a powder comprising 60 wt% zinc recycled and 40 wt% new material, were investigated. The powders were produced from both laboratory and production mills utilizing a typical powder metallurgical process route, that produced spherically shaped, granulated powders in the 45-212 μm size range. Powder screen fractions of 45-63 μm, 90-125 μm and 150-180 μm were studied in detail using an FT4 powder rheometer as well as optical and scanning electron microscopy. Apparent density, flow rate tests and powder rheology revealed that dense granules behaved most consistently, with the smallest differences in flow rates, density and flow energy for differently sized particles, compared to hollow granules. New powder and 100 % zinc recycled powder of the 45-63 μm size range were exposed to 75 % relative humidity for 24 h and experienced higher cohesion, high flow energies and poor rheological behaviour compared to dry powders, independent of their recycling history. Shear and friction tests could not distinguish the powders clearly, while dynamic analysis, aeration, de-aeration, permeability and compressibility tests revealed that the powders' flow energy and response to air depended primarily on particle size and the presence of fines. Zinc recycled powders behaved the same way as new powders if their granule microstructure and particle size distribution was the same, with the formation of ideal dense granules resulting from slurries spray dried with a high yield stress.

研究了四种工业生产的 WC-6wt%Co 粉末的体积特性、形态和粉末流变学。研究了两种粉末，包括 100% 的新鲜原材料、100% 的锌回收粉末以及 60 wt% 的锌回收粉末和 40 wt% 的新材料。这些粉末由实验室和生产工厂利用典型的粉末冶金工艺路线生产而成，可生产出粒度范围为 45-212 μm 的球形颗粒粉末。使用 FT4 粉末流变仪以及光学和扫描电子显微镜对 45-63μm、90-125 μm 和 150-180 μm 的粉末筛分进行了详细研究。表观密度、流速测试和粉末流变学表明，致密颗粒的表现最为一致，与空心颗粒相比，不同大小颗粒的流速、密度和流能差异最小。粒度范围为 45-63 μm 的新粉末和 100% 锌回收粉末在相对湿度为 75% 的环境中暴露 24 小时后，与干粉相比，无论其回收历史如何，都会出现较高的内聚力、较高的流能和较差的流变性能。剪切力和摩擦力测试无法明确区分不同的粉末，而动态分析、通气、除气、渗透性和可压缩性测试表明，粉末的流动能和对空气的反应主要取决于粒度和细粉的存在。如果颗粒的微观结构和粒度分布相同，锌回收粉末的表现与新粉末相同，在高屈服应力下喷雾干燥的浆料会形成理想的致密颗粒。

{"title":"Powder rheology and characterization of new and zinc recycled WC-6wt%Co powders","authors":"C.S. Freemantle , N. Sacks","doi":"10.1016/j.ijrmhm.2024.106889","DOIUrl":"10.1016/j.ijrmhm.2024.106889","url":null,"abstract":"<div><div>Four industrially manufactured WC-6wt%Co powders were studied in terms of bulk properties, morphology and powder rheology. Two powders, comprising 100 % fresh raw material, a 100 % zinc recycled powder and a powder comprising 60 wt% zinc recycled and 40 wt% new material, were investigated. The powders were produced from both laboratory and production mills utilizing a typical powder metallurgical process route, that produced spherically shaped, granulated powders in the 45-212 μm size range. Powder screen fractions of 45-63 μm, 90-125 μm and 150-180 μm were studied in detail using an FT4 powder rheometer as well as optical and scanning electron microscopy. Apparent density, flow rate tests and powder rheology revealed that dense granules behaved most consistently, with the smallest differences in flow rates, density and flow energy for differently sized particles, compared to hollow granules. New powder and 100 % zinc recycled powder of the 45-63 μm size range were exposed to 75 % relative humidity for 24 h and experienced higher cohesion, high flow energies and poor rheological behaviour compared to dry powders, independent of their recycling history. Shear and friction tests could not distinguish the powders clearly, while dynamic analysis, aeration, de-aeration, permeability and compressibility tests revealed that the powders' flow energy and response to air depended primarily on particle size and the presence of fines. Zinc recycled powders behaved the same way as new powders if their granule microstructure and particle size distribution was the same, with the formation of ideal dense granules resulting from slurries spray dried with a high yield stress.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"125 ","pages":"Article 106889"},"PeriodicalIF":4.2,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Size-dependent mechanical responses of twinned Nanocrystalline HfNbZrTi refractory high-entropy alloy 孪晶纳米铌锆钛耐火高熵合金的尺寸依赖性力学响应

IF 4.2 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Refractory Metals & Hard Materials

Pub Date : 2024-09-21 DOI: 10.1016/j.ijrmhm.2024.106885

Yihan Wu, Zhiwen Bai, Gaosheng Yan, Wenshan Yu, Shengping Shen

Atomistic simulations are performed to study the size-dependent mechanical responses of HfNbZrTi refractory high-entropy alloy (RHEA) containing ultrafine grains and highly oriented twin boundaries (TBs). The strength and flow stress of nanocrystalline RHEA (NC-RHEA) under tensile loadings are explored versus decreasing grain size d. The transition from classical Hall-Petch (HP) strengthening to inverse HP softening at a critical grain size d_c = 5.91 nm is attributed to the change of plastic deformation mechanisms from dislocation emission and phase transformation to grain boundary (GB) activities. Besides, the intragranular TBs considerably enhance the strength of nanotwinned RHEA (NT-RHEA); the enhancing effect reduces with decreasing twin thickness λ. As the volume fraction of GB increases with decreasing d, GB activities dominate the plasticity of NT-RHEA and cause comparable mechanical properties with NC-RHEA. Moreover, the influences of dislocation glide, phase transformation and twinning on the mechanical properties of RHEA are quantified and separately analyzed to further verify our simulation results. Findings of this study not only promote insights into the nanostructure-property relation of HfNbZrTi, but also shed the light on performance enhancement through nanostructural design.

原子模拟研究了含有超细晶粒和高取向孪晶边界（TBs）的 HfNbZrTi 难熔高熵合金（RHEA）随尺寸变化的力学响应。在临界晶粒尺寸 dc = 5.91 nm 时，从经典霍尔-佩奇（HP）强化到反向 HP 软化的转变归因于塑性变形机制从位错发射和相变到晶界（GB）活动的变化。此外，粒内 TB 显著增强了纳米孪晶 RHEA（NT-RHEA）的强度；增强效应随孪晶厚度 λ 的减小而减弱。随着 GB 体积分数随 d 的减小而增加，GB 活动主导了 NT-RHEA 的塑性，并使其具有与 NC-RHEA 相当的机械性能。此外，还量化并分别分析了位错滑行、相变和孪晶对 RHEA 力学性能的影响，进一步验证了我们的模拟结果。本研究的结果不仅有助于深入了解 HfNbZrTi 的纳米结构与性能之间的关系，还有助于通过纳米结构设计提高其性能。

{"title":"Size-dependent mechanical responses of twinned Nanocrystalline HfNbZrTi refractory high-entropy alloy","authors":"Yihan Wu, Zhiwen Bai, Gaosheng Yan, Wenshan Yu, Shengping Shen","doi":"10.1016/j.ijrmhm.2024.106885","DOIUrl":"10.1016/j.ijrmhm.2024.106885","url":null,"abstract":"<div><div>Atomistic simulations are performed to study the size-dependent mechanical responses of HfNbZrTi refractory high-entropy alloy (RHEA) containing ultrafine grains and highly oriented twin boundaries (TBs). The strength and flow stress of nanocrystalline RHEA (NC-RHEA) under tensile loadings are explored versus decreasing grain size <em>d</em>. The transition from classical Hall-Petch (HP) strengthening to inverse HP softening at a critical grain size <em>d</em><sub>c</sub> = 5.91 nm is attributed to the change of plastic deformation mechanisms from dislocation emission and phase transformation to grain boundary (GB) activities. Besides, the intragranular TBs considerably enhance the strength of nanotwinned RHEA (NT-RHEA); the enhancing effect reduces with decreasing twin thickness <em>λ</em>. As the volume fraction of GB increases with decreasing <em>d</em>, GB activities dominate the plasticity of NT-RHEA and cause comparable mechanical properties with NC-RHEA. Moreover, the influences of dislocation glide, phase transformation and twinning on the mechanical properties of RHEA are quantified and separately analyzed to further verify our simulation results. Findings of this study not only promote insights into the nanostructure-property relation of HfNbZrTi, but also shed the light on performance enhancement through nanostructural design.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"125 ","pages":"Article 106885"},"PeriodicalIF":4.2,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0