Pub Date : 2024-11-05DOI: 10.1016/j.scriptamat.2024.116442
Marshall B. Frye , Jonathan R. Chin , Matthew Barone , Steven E. Zeltmann , Lauren M. Garten
Developing routes to deposit highly conductive (111) oriented platinum films with sub-nanometer roughness will provide a platform to develop unique hexagonal and (111) oriented cubic materials. A two-temperature e-beam deposition process is proposed for the growth of (111) oriented platinum films on Al2O3 to simultaneously induce crystallographic texturing, improve conductivity, and reduce surface roughness. Depositing an initial platinum layer at 700 °C induces texturing then subsequently depositing at 500 °C promotes planar growth. The resulting (111) platinum films exhibit a narrow rocking curve full width at half maximum of 0.004°, a surface roughness of 0.20 nm, and conductivity of 8.99 × 106 S/m simultaneously—reaching metrics that are not currently available by other deposition methods. The e-beam deposition methodology developed in this study provides a route to increase the performance of platinum as a conductive substrate.
{"title":"Enhancing the conductivity and crystallinity of (111) platinum films via a two-temperature deposition and substrate annealing","authors":"Marshall B. Frye , Jonathan R. Chin , Matthew Barone , Steven E. Zeltmann , Lauren M. Garten","doi":"10.1016/j.scriptamat.2024.116442","DOIUrl":"10.1016/j.scriptamat.2024.116442","url":null,"abstract":"<div><div>Developing routes to deposit highly conductive (111) oriented platinum films with sub-nanometer roughness will provide a platform to develop unique hexagonal and (111) oriented cubic materials. A two-temperature e-beam deposition process is proposed for the growth of (111) oriented platinum films on Al<sub>2</sub>O<sub>3</sub> to simultaneously induce crystallographic texturing, improve conductivity, and reduce surface roughness. Depositing an initial platinum layer at 700 °C induces texturing then subsequently depositing at 500 °C promotes planar growth. The resulting (111) platinum films exhibit a narrow rocking curve full width at half maximum of 0.004°, a surface roughness of 0.20 nm, and conductivity of 8.99 × 10<sup>6</sup> S/m simultaneously—reaching metrics that are not currently available by other deposition methods. The e-beam deposition methodology developed in this study provides a route to increase the performance of platinum as a conductive substrate.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"256 ","pages":"Article 116442"},"PeriodicalIF":5.3,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586217","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}
Pub Date : 2024-11-04DOI: 10.1016/j.scriptamat.2024.116445
Changming Fang, Yun Wang, Zhongyun Fan
The mechanism of ‘Si poisoning’ of Al-Ti-B based grain-refiners in Al-Si alloys has been a topic of intensive study for over half a century. We here investigate prenucleation of Al at the Si segregated interfaces between liquid Al and TiB2{0001} substrates using ab initio techniques. Our study reveals that chemical affinity between Ti and Si atoms empowers Si segregation at the Al(l)/substrate interface during solidification. The Si interfacial segregation curbs atomic ordering in the liquid Al adjacent to the substrate. Consequently, prenucleation of Al atoms at the Al(l)/{0001}TiB2 interface is deteriorated and thus, the subsequent nucleation process adversely affected, which causes the so-called ‘Si poisoning’ effect during the practice of grain refinement via inoculation with addition of TiB2 particles in Al-Si alloys.
半个多世纪以来，人们一直在深入研究铝硅合金中基于铝-钛-B 晶粒的 "硅中毒 "机制。在此，我们使用 ab initio 技术研究了铝在液态铝和 TiB2{0001} 基质之间的硅偏析界面上的预成核现象。我们的研究发现，在凝固过程中，Ti 原子和 Si 原子间的化学亲和力会促进 Al(l)/ 基底界面上的硅偏析。硅界面偏析抑制了邻近基底的液态铝中的原子有序性。因此，Al(l)/{0001}TiB2 界面上的 Al 原子预成核会恶化，从而对随后的成核过程产生不利影响，这就造成了在 Al-Si 合金中通过接种添加 TiB2 粒子进行晶粒细化时的所谓 "Si 中毒 "效应。
{"title":"Si segregation deters prenucleation at the interfaces between liquid-aluminum and TiB2 substrates, the origin of ‘Si poisoning’","authors":"Changming Fang, Yun Wang, Zhongyun Fan","doi":"10.1016/j.scriptamat.2024.116445","DOIUrl":"10.1016/j.scriptamat.2024.116445","url":null,"abstract":"<div><div>The mechanism of ‘Si poisoning’ of Al-Ti-B based grain-refiners in Al-Si alloys has been a topic of intensive study for over half a century. We here investigate prenucleation of Al at the Si segregated interfaces between liquid Al and TiB<sub>2</sub>{0001} substrates using <em>ab initio</em> techniques. Our study reveals that chemical affinity between Ti and Si atoms empowers Si segregation at the Al(l)/substrate interface during solidification. The Si interfacial segregation curbs atomic ordering in the liquid Al adjacent to the substrate. Consequently, prenucleation of Al atoms at the Al(l)/{0001}TiB<sub>2</sub> interface is deteriorated and thus, the subsequent nucleation process adversely affected, which causes the so-called ‘Si poisoning’ effect during the practice of grain refinement via inoculation with addition of TiB<sub>2</sub> particles in Al-Si alloys.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"256 ","pages":"Article 116445"},"PeriodicalIF":5.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578971","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}
Pub Date : 2024-11-01DOI: 10.1016/j.scriptamat.2024.116441
Bo Liu , Dong Han , Tianrun Li , Jingping Cui , Ziwei Zhang , Guofeng Han , Xiaoming Wang , Baijun Yang , Jianqiang Wang
A problem has recently been highlighted in the additively manufactured (AMed) L12-strengthened high/medium-entropy alloys (H/MEAs), where the dislocation strengthening effect will be severely weakened due to the inevitable dislocation recovery that occurs during the aging process. To address this, a cyclic deep cryogenic strategy (CDCS) towards the dislocation-precipitation strengthening synergy is proposed. Besides dislocations, this strategy can introduce dense intersecting stacking faults, thus effectively enhancing the thermal stability of dislocations during aging due to the pinning effect of Lomer-Cottrell locking. The existence of these high-density defects further ensures the uniform precipitation of L12 phase. Significantly, the CDCS causes a substantial ⁓ 40% increase in the yield strength of the (CoCrNi)94Al3Ti3 MEA sample without compromising the ductility, in which the contribution of dislocation strengthening is doubled. This work provides a pathway for obtaining high-performance AMed H/MEAs, especially L12-strengthened H/MEAs.
{"title":"Achieving dislocation-precipitation strengthening synergy in additively manufactured medium-entropy alloy via cyclic deep cryogenic strategy","authors":"Bo Liu , Dong Han , Tianrun Li , Jingping Cui , Ziwei Zhang , Guofeng Han , Xiaoming Wang , Baijun Yang , Jianqiang Wang","doi":"10.1016/j.scriptamat.2024.116441","DOIUrl":"10.1016/j.scriptamat.2024.116441","url":null,"abstract":"<div><div>A problem has recently been highlighted in the additively manufactured (AMed) L1<sub>2</sub>-strengthened high/medium-entropy alloys (H/MEAs), where the dislocation strengthening effect will be severely weakened due to the inevitable dislocation recovery that occurs during the aging process. To address this, a cyclic deep cryogenic strategy (CDCS) towards the dislocation-precipitation strengthening synergy is proposed. Besides dislocations, this strategy can introduce dense intersecting stacking faults, thus effectively enhancing the thermal stability of dislocations during aging due to the pinning effect of Lomer-Cottrell locking. The existence of these high-density defects further ensures the uniform precipitation of L1<sub>2</sub> phase. Significantly, the CDCS causes a substantial ⁓ 40% increase in the yield strength of the (CoCrNi)<sub>94</sub>Al<sub>3</sub>Ti<sub>3</sub> MEA sample without compromising the ductility, in which the contribution of dislocation strengthening is doubled. This work provides a pathway for obtaining high-performance AMed H/MEAs, especially L1<sub>2</sub>-strengthened H/MEAs.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"256 ","pages":"Article 116441"},"PeriodicalIF":5.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571865","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}
Pub Date : 2024-11-01DOI: 10.1016/j.scriptamat.2024.116436
Panmei Liu, Shuo Ma, Zetao Mou, Yongchang Liu, Zumin Wang
Strong interactions of metal nanoparticles (NPs) with oxide matrices can dramatically enhance the thermal stability of metal NPs. However, how metal-oxide interactions control the growth of metal NPs remains unclear. Here, the growth of Pt NPs with respect to metal-oxide interactions was investigated by encapsulating them in different Al2O3 and SiO2 oxides. Pt NPs encapsulated in Al2O3 exhibited excellent thermal stability than those in SiO2. Quantitative thermodynamic calculations revealed that metal-oxide interactions strongly governed the driving force for the coalescence of Pt in Al2O3 and SiO2. The kinetic analysis further showed that stronger Pt-Al2O3 interactions controlled the Ostwald ripening of Pt NPs by restricting the diffusion of Pt atoms in oxides, leading to a higher growth activation energy of Pt in Al2O3 than SiO2. These findings explain the different sinter resistance of metal NPs when encapsulated in different oxides, providing valuable insights for enhancing the thermal stability of metal NPs.
{"title":"Study on the growth mechanism of Pt nanoparticles in oxides: Role of metal-oxide interactions","authors":"Panmei Liu, Shuo Ma, Zetao Mou, Yongchang Liu, Zumin Wang","doi":"10.1016/j.scriptamat.2024.116436","DOIUrl":"10.1016/j.scriptamat.2024.116436","url":null,"abstract":"<div><div>Strong interactions of metal nanoparticles (NPs) with oxide matrices can dramatically enhance the thermal stability of metal NPs. However, how metal-oxide interactions control the growth of metal NPs remains unclear. Here, the growth of Pt NPs with respect to metal-oxide interactions was investigated by encapsulating them in different Al<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub> oxides. Pt NPs encapsulated in Al<sub>2</sub>O<sub>3</sub> exhibited excellent thermal stability than those in SiO<sub>2</sub>. Quantitative thermodynamic calculations revealed that metal-oxide interactions strongly governed the driving force for the coalescence of Pt in Al<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub>. The kinetic analysis further showed that stronger Pt-Al<sub>2</sub>O<sub>3</sub> interactions controlled the Ostwald ripening of Pt NPs by restricting the diffusion of Pt atoms in oxides, leading to a higher growth activation energy of Pt in Al<sub>2</sub>O<sub>3</sub> than SiO<sub>2</sub>. These findings explain the different sinter resistance of metal NPs when encapsulated in different oxides, providing valuable insights for enhancing the thermal stability of metal NPs.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"256 ","pages":"Article 116436"},"PeriodicalIF":5.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571866","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}
Pub Date : 2024-11-01DOI: 10.1016/j.scriptamat.2024.116439
Weiqiang Hu , Zhu Qian , ZuPeng Yan , Guizhen Shi , Xia Sun , Zongqing Ma , Yongchang Liu
In order to alleviate the difficulties of coarse grains and poor mechanical properties in traditional hot worked bulk W alloys, we designed the entire chain preparation process including two-step freeze-drying, multi-step low temperature sintering and multi-step hot pressing. As a result, the hot worked bulk W-Y2O3 alloy in this work features finest grain size (650 nm) and finer subgrains, ultrafine intergranular and intragranular oxide nanoparticles (<50 nm), novel oxide compositions (Y2WO6 or Y2O3@Y2WO6 core-shell phase), and specific W(110)/Y2WO6 (232) (400), (432) or (2) coherent phase interfaces. Furthermore, the above microstructure characteristics endow W-Y2O3 alloy with highest strength (1401.0 MPa, 1284.4 MPa and 1039.1 MPa at 100 °C, 200 °C and 600 °C repectively), excellent ductility and outstanding structure thermal stability compare to traditional bulk ODS W alloy, which points out a new direction for the development of ex-situ precipitated second phase dispersion strengthened refractory metals.
{"title":"Controllable preparation of ultrafine bulk ODS W alloy with ultrahigh strength and improved ductility","authors":"Weiqiang Hu , Zhu Qian , ZuPeng Yan , Guizhen Shi , Xia Sun , Zongqing Ma , Yongchang Liu","doi":"10.1016/j.scriptamat.2024.116439","DOIUrl":"10.1016/j.scriptamat.2024.116439","url":null,"abstract":"<div><div>In order to alleviate the difficulties of coarse grains and poor mechanical properties in traditional hot worked bulk W alloys, we designed the entire chain preparation process including two-step freeze-drying, multi-step low temperature sintering and multi-step hot pressing. As a result, the hot worked bulk W-Y<sub>2</sub>O<sub>3</sub> alloy in this work features finest grain size (650 nm) and finer subgrains, ultrafine intergranular and intragranular oxide nanoparticles (<50 nm), novel oxide compositions (Y<sub>2</sub>WO<sub>6</sub> or Y<sub>2</sub>O<sub>3</sub>@Y<sub>2</sub>WO<sub>6</sub> core-shell phase), and specific W(110)/Y<sub>2</sub>WO<sub>6</sub> (232) (400), (432) or (<span><math><mrow><mover><mn>2</mn><mo>¯</mo></mover><mover><mn>2</mn><mo>¯</mo></mover></mrow></math></span>2) coherent phase interfaces. Furthermore, the above microstructure characteristics endow W-Y<sub>2</sub>O<sub>3</sub> alloy with highest strength (1401.0 MPa, 1284.4 MPa and 1039.1 MPa at 100 °C, 200 °C and 600 °C repectively), excellent ductility and outstanding structure thermal stability compare to traditional bulk ODS W alloy, which points out a new direction for the development of <em>ex-situ</em> precipitated second phase dispersion strengthened refractory metals.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"256 ","pages":"Article 116439"},"PeriodicalIF":5.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571868","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}
Pub Date : 2024-11-01DOI: 10.1016/j.scriptamat.2024.116443
Tao Chen , Pengfei Yu , Yusi Li , Yan Chen , Chao Yang , Rocco Lupoi , Shuo Yin , Xinyu Zhang
In this study, it is revealed for the first time that ultra-high-speed impact can trigger in-situ dehydrogenation at the impact interface of titanium hydride (TiH). This phenomenon leads to a phase transformation from brittle TiH to ductile Ti, causing a shift in the ductile-to-brittle transition from the impact interface to the particle interior. Inspired by this unique behavior, and considering the mechanical interactions between particles during the spray process, TiH powders were used as feedstock to successfully produce a large-scale random cellular structure through cold spray. A systematic investigation of the deposition process revealed that unbroken TiH particles interact with dehydrogenated ones, resulting in only the ductile portion of the TiH particle being deposited, while the brittle interior is spalled off, consequently forming the “walls” of the cellular structures. This work highlights the potential of TiH powders to advance cold spray technology, particularly in the creation of complex cellular structures.
本研究首次揭示了超高速撞击可引发氢化钛（TiH）撞击界面的原位脱氢。这种现象导致脆性 TiH 向韧性 Ti 的相变，使韧性向脆性的转变从冲击界面转移到颗粒内部。受这种独特行为的启发，并考虑到喷涂过程中颗粒之间的机械相互作用，TiH 粉末被用作原料，通过冷喷涂成功生产出大规模随机蜂窝结构。对沉积过程的系统研究表明，未破碎的 TiH 颗粒与脱氢的 TiH 颗粒相互作用，导致只有 TiH 颗粒的韧性部分被沉积，而脆性内部被剥落，从而形成蜂窝结构的 "壁"。这项工作凸显了 TiH 粉末推动冷喷技术发展的潜力，尤其是在创建复杂蜂窝结构方面。
{"title":"High speed impact induced dehydrogenation of titanium hydride and formation of cellular structure via cold spray","authors":"Tao Chen , Pengfei Yu , Yusi Li , Yan Chen , Chao Yang , Rocco Lupoi , Shuo Yin , Xinyu Zhang","doi":"10.1016/j.scriptamat.2024.116443","DOIUrl":"10.1016/j.scriptamat.2024.116443","url":null,"abstract":"<div><div>In this study, it is revealed for the first time that ultra-high-speed impact can trigger in-situ dehydrogenation at the impact interface of titanium hydride (TiH). This phenomenon leads to a phase transformation from brittle TiH to ductile Ti, causing a shift in the ductile-to-brittle transition from the impact interface to the particle interior. Inspired by this unique behavior, and considering the mechanical interactions between particles during the spray process, TiH powders were used as feedstock to successfully produce a large-scale random cellular structure through cold spray. A systematic investigation of the deposition process revealed that unbroken TiH particles interact with dehydrogenated ones, resulting in only the ductile portion of the TiH particle being deposited, while the brittle interior is spalled off, consequently forming the “walls” of the cellular structures. This work highlights the potential of TiH powders to advance cold spray technology, particularly in the creation of complex cellular structures.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"256 ","pages":"Article 116443"},"PeriodicalIF":5.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571867","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}
Pub Date : 2024-10-31DOI: 10.1016/j.scriptamat.2024.116438
Xiaoli Luo , Weiji Lai , Yuxi He , Xincheng Xu , Qihang Xu , Deqiang You , Sheng Cao , Wei Li , Xiaojian Wang
Ti-Zr-Nb-Ta-Mo refractory multi-principal element alloys typically exhibit high yield strength while tensile ductility tends to be poor. In this study, we found that even after solid solution treatment of Ti-Zr-Nb-Ta-Mo alloys, significant change in ductility occur due to the local chemical fluctuations. Ta's dramatic chemical fluctuations cause variations in atomic-scale strain fields, leading to reduced grain boundary strength and brittle fracture. First-principles calculations show that (Ti, Zr)-rich at the grain boundaries increases the delocalization of valence electrons, leading to longer bond lengths and reduced crystal orbital bond index values, thereby causing grain boundary embrittlement. Our findings explore the root causes of brittleness in Ti-Zr-Nb-Ta-Mo alloys at the atomic and electronic scales, providing not only a method to analyze grain boundary embrittlement using bond length, electronic localization function and crystal orbital bond index, but also a theoretical guidance for improving the mechanical properties via grain boundary structure optimization.
{"title":"Correlations between local chemical fluctuations and grain boundary strength in Ti-Zr-Nb-Ta-Mo refractory multi-principal element alloys","authors":"Xiaoli Luo , Weiji Lai , Yuxi He , Xincheng Xu , Qihang Xu , Deqiang You , Sheng Cao , Wei Li , Xiaojian Wang","doi":"10.1016/j.scriptamat.2024.116438","DOIUrl":"10.1016/j.scriptamat.2024.116438","url":null,"abstract":"<div><div>Ti-Zr-Nb-Ta-Mo refractory multi-principal element alloys typically exhibit high yield strength while tensile ductility tends to be poor. In this study, we found that even after solid solution treatment of Ti-Zr-Nb-Ta-Mo alloys, significant change in ductility occur due to the local chemical fluctuations. Ta's dramatic chemical fluctuations cause variations in atomic-scale strain fields, leading to reduced grain boundary strength and brittle fracture. First-principles calculations show that (Ti, Zr)-rich at the grain boundaries increases the delocalization of valence electrons, leading to longer bond lengths and reduced crystal orbital bond index values, thereby causing grain boundary embrittlement. Our findings explore the root causes of brittleness in Ti-Zr-Nb-Ta-Mo alloys at the atomic and electronic scales, providing not only a method to analyze grain boundary embrittlement using bond length, electronic localization function and crystal orbital bond index, but also a theoretical guidance for improving the mechanical properties via grain boundary structure optimization.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"256 ","pages":"Article 116438"},"PeriodicalIF":5.3,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142560537","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}
Pub Date : 2024-10-30DOI: 10.1016/j.scriptamat.2024.116431
Chengpeng Liu, Xiang-Xi Ye, Hefei Huang
In this study, the in-situ TEM tensile experiment was performed on the Nb-modified GH3535 alloy after He ion irradiation at 750 °C, to investigate the influence of the nano twins on the evolution of irradiation-induced He bubbles under thermo-mechanical coupling conditions. The results suggest that the interaction between the He bubbles and nano twins may contribute to the abnormal irradiation hardening observed in Nb-GH3535 alloy, in addition to the effects of the He bubbles and precipitate strengthening. Moreover, the merger and coarsening of the He bubbles under the influence of the nano twins provide direct experimental evidence supporting the previously proposed stress-assisted coarsening mechanism for the He bubbles.
本研究对 750 ℃ He 离子辐照后的 Nb 改性 GH3535 合金进行了原位 TEM 拉伸实验，以研究纳米孪晶在热机械耦合条件下对辐照诱导 He 气泡演化的影响。结果表明，除了氦气泡和沉淀强化的影响之外，氦气泡和纳米孪晶之间的相互作用也可能导致在 Nb-GH3535 合金中观察到的异常辐照硬化。此外，氦泡在纳米孪晶影响下的合并和粗化为之前提出的氦泡应力辅助粗化机制提供了直接的实验证据。
{"title":"In-situ TEM investigation of the effect of nano twins on the evolution of He bubbles under thermo-mechanical coupling conditions","authors":"Chengpeng Liu, Xiang-Xi Ye, Hefei Huang","doi":"10.1016/j.scriptamat.2024.116431","DOIUrl":"10.1016/j.scriptamat.2024.116431","url":null,"abstract":"<div><div>In this study, the <em>in-situ</em> TEM tensile experiment was performed on the Nb-modified GH3535 alloy after He ion irradiation at 750 °C, to investigate the influence of the nano twins on the evolution of irradiation-induced He bubbles under thermo-mechanical coupling conditions. The results suggest that the interaction between the He bubbles and nano twins may contribute to the abnormal irradiation hardening observed in Nb-GH3535 alloy, in addition to the effects of the He bubbles and precipitate strengthening. Moreover, the merger and coarsening of the He bubbles under the influence of the nano twins provide direct experimental evidence supporting the previously proposed stress-assisted coarsening mechanism for the He bubbles.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"256 ","pages":"Article 116431"},"PeriodicalIF":5.3,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552874","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}
Pub Date : 2024-10-30DOI: 10.1016/j.scriptamat.2024.116429
Meizhong Lyu , Zipeng Xu , Gregory S. Rohrer , Elizabeth A. Holm
This study employed experimental data as the initial microstructure for molecular dynamics simulation of grain growth in polycrystalline nickel, aiming to investigate the relationship between grain boundary curvature and velocity in impurity-free systems. A bidirectional method for converting data between voxelized and atomic structures was developed and validated. The outcomes of the MD grain growth simulation broadly matched the characteristics of grain growth observed in the experiment. Most significantly, the simulation result contributes additional evidence supporting the reported absence of a correlation between velocity and curvature during grain growth in polycrystals, and confirms that this is not related to solutes, precipitates, processing route, or characterization method. The implication is that features of the 3D grain boundary network interfere with the velocity/curvature relationship.
{"title":"Comparing molecular dynamics simulations of grain growth with experimental data","authors":"Meizhong Lyu , Zipeng Xu , Gregory S. Rohrer , Elizabeth A. Holm","doi":"10.1016/j.scriptamat.2024.116429","DOIUrl":"10.1016/j.scriptamat.2024.116429","url":null,"abstract":"<div><div>This study employed experimental data as the initial microstructure for molecular dynamics simulation of grain growth in polycrystalline nickel, aiming to investigate the relationship between grain boundary curvature and velocity in impurity-free systems. A bidirectional method for converting data between voxelized and atomic structures was developed and validated. The outcomes of the MD grain growth simulation broadly matched the characteristics of grain growth observed in the experiment. Most significantly, the simulation result contributes additional evidence supporting the reported absence of a correlation between velocity and curvature during grain growth in polycrystals, and confirms that this is not related to solutes, precipitates, processing route, or characterization method. The implication is that features of the 3D grain boundary network interfere with the velocity/curvature relationship.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"256 ","pages":"Article 116429"},"PeriodicalIF":5.3,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552876","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}
Pub Date : 2024-10-30DOI: 10.1016/j.scriptamat.2024.116432
Lei Zhang , Juan Ding , Jiatao Zhou , Baishan Chen , Yunzhu Ma , Yufeng Huang , Chaoping Liang , Wensheng Liu
Tungsten(W) with the strongest metallic bonding and the highest melting point among metals, presents no phase transition before the melting temperature. Here we report the pristine body-centered cubic (BCC) α to metastable ω phase transformation in polycrystalline W under high-energy laser shock. The formation of ω phase is triggered by the collapse of atoms on two adjacent (111)α plane toward each other along <111>α direction. HADDF-STEM clearly shows the transition state hexagonal and the ideal ω phase form sequentially along the BCC/ω phase interface through different atomic displacement. First-principles calculations reveal that the energy required for BCC to ω transformation could be met at isostatic pressure lower than 200 GPa, which falls with the local stress concentration range of shock loading. Our findings not only unravel the new BCC/ω phase transition in W, but also shed lights to the plastic deformation mechanisms of strongly bonded materials under extreme shock loading.
{"title":"Deformation-induced ω phase transition in polycrystalline tungsten under extreme shock loading","authors":"Lei Zhang , Juan Ding , Jiatao Zhou , Baishan Chen , Yunzhu Ma , Yufeng Huang , Chaoping Liang , Wensheng Liu","doi":"10.1016/j.scriptamat.2024.116432","DOIUrl":"10.1016/j.scriptamat.2024.116432","url":null,"abstract":"<div><div>Tungsten(W) with the strongest metallic bonding and the highest melting point among metals, presents no phase transition before the melting temperature. Here we report the pristine body-centered cubic (BCC) α to metastable ω phase transformation in polycrystalline W under high-energy laser shock. The formation of ω phase is triggered by the collapse of atoms on two adjacent (111)α plane toward each other along <111>α direction. HADDF-STEM clearly shows the transition state hexagonal and the ideal ω phase form sequentially along the BCC/ω phase interface through different atomic displacement. First-principles calculations reveal that the energy required for BCC to ω transformation could be met at isostatic pressure lower than 200 GPa, which falls with the local stress concentration range of shock loading. Our findings not only unravel the new BCC/ω phase transition in W, but also shed lights to the plastic deformation mechanisms of strongly bonded materials under extreme shock loading.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"256 ","pages":"Article 116432"},"PeriodicalIF":5.3,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552877","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}
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