Pub Date : 2024-09-26DOI: 10.1016/j.intermet.2024.108501
Manish Kumar Singh , B. Nithin , Kesavan Ravi , M.R. Rahul
Eutectic high entropy alloys (EHEAs) with hard and ductile phases are promising for high-temperature applications. The mechanical properties of EHEAs can be improved by incorporating precipitates in the ductile phase. The study focuses on the CALPHAD-guided alloy design approach for developing EHEA with cuboidal L12 precipitates in the ductile phase. The newly designed alloy (Al0.17CoCrFeNiTa0.22) is subjected to a simulation-guided heat treatment cycle. The Al0.17CoCrFeNiTa0.22 alloy shows FCC phase with a needle-like Ta-rich precipitate at 12 h and Ni-Al-rich cuboidal precipitate at 24 h of heat treatment. The calculated entropy of mixing of cuboidal precipitate is higher than that of needle-like precipitate. The detailed TEM characterisation confirms the characteristics of precipitates and microstructural changes correlated with microhardness measurements. The study proposes a novel EHEA system with a nano-scale precipitation-strengthened FCC phase and eutectic colony.
{"title":"Simulation-guided design of novel precipitation-strengthened eutectic high entropy alloy","authors":"Manish Kumar Singh , B. Nithin , Kesavan Ravi , M.R. Rahul","doi":"10.1016/j.intermet.2024.108501","DOIUrl":"10.1016/j.intermet.2024.108501","url":null,"abstract":"<div><div>Eutectic high entropy alloys (EHEAs) with hard and ductile phases are promising for high-temperature applications. The mechanical properties of EHEAs can be improved by incorporating precipitates in the ductile phase. The study focuses on the CALPHAD-guided alloy design approach for developing EHEA with cuboidal L1<sub>2</sub> precipitates in the ductile phase. The newly designed alloy (Al<sub>0.17</sub>CoCrFeNiTa<sub>0.22</sub>) is subjected to a simulation-guided heat treatment cycle. The Al<sub>0.17</sub>CoCrFeNiTa<sub>0.22</sub> alloy shows FCC phase with a needle-like Ta-rich precipitate at 12 h and Ni-Al-rich cuboidal precipitate at 24 h of heat treatment. The calculated entropy of mixing of cuboidal precipitate is higher than that of needle-like precipitate. The detailed TEM characterisation confirms the characteristics of precipitates and microstructural changes correlated with microhardness measurements. The study proposes a novel EHEA system with a nano-scale precipitation-strengthened FCC phase and eutectic colony.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108501"},"PeriodicalIF":4.3,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323311","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 : 2024-09-26DOI: 10.1016/j.intermet.2024.108467
Ding Zhou , Bing Hou , Yaqi Lin , Bingjin Li , Tianyan Liu , Hongwei Qiao , Lei Sun , Pengzhou Li , Yulong Li
The concomitant of relatively ductile-like shear banding and brittle-like fracture in metallic glasses makes their failure origin, i.e., how shear bands developing into cracks, a concerned issue to reveal the unique properties of the amorphous metals. Such shear-band-to-crack transition (SCT) is prominently influenced by loading rate and temperature, whereas their roles are usually ambiguous. In this paper, serial quasi-static and dynamic tests at ambient and cryogenic temperatures were performed to clarify the roles of strain rate and temperature during SCT in a Zr-based bulk metallic glass (BMG) by an electronic testing machine and a modified split Hopkinson pressure bar (SHPB) system, respectively. Strain rates were set from 10−3 s−1 to 103 s−1 and temperatures were set from 173 K to 293 K. In-situ and post-fracture SCT patterns have been captured by high-speed photographing and scan electronic microscopy (SEM), which show a strong relevance to shear-band decohesion. Comparisons between SCT patterns under various loading conditions have clarified that loading rate controls decohesion distribution while temperature controls decohesion resistance. A decohesion-tendency ratio of applied energy to critical decohesion resistance is established from an energy-based view, and rate and temperature dependence of the ratio is discussed to figure out how these two effects determining different decohesion behavior and subsequent SCT patterns in BMGs.
{"title":"The roles of loading rate and temperature during shear-band-to-crack transition (SCT) in bulk metallic glasses: A study of quasi-static and dynamic shearing performances at ambient and cryogenic temperatures","authors":"Ding Zhou , Bing Hou , Yaqi Lin , Bingjin Li , Tianyan Liu , Hongwei Qiao , Lei Sun , Pengzhou Li , Yulong Li","doi":"10.1016/j.intermet.2024.108467","DOIUrl":"10.1016/j.intermet.2024.108467","url":null,"abstract":"<div><div>The concomitant of relatively ductile-like shear banding and brittle-like fracture in metallic glasses makes their failure origin, i.e., how shear bands developing into cracks, a concerned issue to reveal the unique properties of the amorphous metals. Such shear-band-to-crack transition (SCT) is prominently influenced by loading rate and temperature, whereas their roles are usually ambiguous. In this paper, serial quasi-static and dynamic tests at ambient and cryogenic temperatures were performed to clarify the roles of strain rate and temperature during SCT in a Zr-based bulk metallic glass (BMG) by an electronic testing machine and a modified split Hopkinson pressure bar (SHPB) system, respectively. Strain rates were set from 10<sup>−3</sup> s<sup>−1</sup> to 10<sup>3</sup> s<sup>−1</sup> and temperatures were set from 173 K to 293 K. In-situ and post-fracture SCT patterns have been captured by high-speed photographing and scan electronic microscopy (SEM), which show a strong relevance to shear-band decohesion. Comparisons between SCT patterns under various loading conditions have clarified that loading rate controls decohesion distribution while temperature controls decohesion resistance. A decohesion-tendency ratio of applied energy to critical decohesion resistance is established from an energy-based view, and rate and temperature dependence of the ratio is discussed to figure out how these two effects determining different decohesion behavior and subsequent SCT patterns in BMGs.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108467"},"PeriodicalIF":4.3,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323309","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 : 2024-09-26DOI: 10.1016/j.intermet.2024.108509
Lingchen Kong, Chuanwei Shi, Xuan Hao, Shenhao Wang, Yushuang Huo, Zhiheng Zhu, Junhua Sun
The HEA coatings of FeCoCrNiMnTixMo1.5-x(x = 0.25, 0.5, 0.75, 1 and 1.25) were prepared by laser cladding. X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and scanning electron microscopy (SEM) were used to characterize the phase and crystal structure. The mechanical properties were tested. The results show that Ti is solidly dissolved in the FCC phase for solid solution strengthening. Mo is precipitated as the second phase σ phase for second phase dispersion strengthening. As x increases, the coating becomes the FCC+σ phase, and the σ phase disappears at x = 1.25. The microhardness and wear resistance of the coating are greatly improved by solution strengthening and second phase precipitation strengthening. The microhardness is up to 3.18 times of the substrate, and the wear resistance is up to 10.9 times of the substrate. Corrosion resistance of all coatings is better than that of 45# steel. With the increase of x, the corrosion resistance of the coating increases first and then decreases. When x = 1, the corrosion resistance of the coating is the best.
通过激光熔覆制备了铁钴铬镍锰铁合金 1.5-x（x = 0.25、0.5、0.75、1 和 1.25）的 HEA 涂层。利用 X 射线衍射 (XRD)、电子反向散射衍射 (EBSD) 和扫描电子显微镜 (SEM) 表征了相和晶体结构。同时还测试了其机械性能。结果表明，钛固溶在 FCC 相中，用于固溶强化。钼作为第二相σ相析出，用于第二相分散强化。随着 x 的增加，涂层变成了 FCC+σ 相，σ 相在 x = 1.25 时消失。通过溶液强化和第二相沉淀强化，涂层的显微硬度和耐磨性大大提高。涂层的显微硬度是基体的 3.18 倍，耐磨性是基体的 10.9 倍。所有涂层的耐腐蚀性均优于 45#钢。随着 x 的增大，涂层的耐腐蚀性先增大后减小。当 x = 1 时，涂层的耐腐蚀性最好。
{"title":"Effect of Ti and Mo content changes on microstructure and properties of laser cladding FeCoCrNiMn high entropy alloy coatings","authors":"Lingchen Kong, Chuanwei Shi, Xuan Hao, Shenhao Wang, Yushuang Huo, Zhiheng Zhu, Junhua Sun","doi":"10.1016/j.intermet.2024.108509","DOIUrl":"10.1016/j.intermet.2024.108509","url":null,"abstract":"<div><div>The HEA coatings of FeCoCrNiMnTixMo1.5-x(x = 0.25, 0.5, 0.75, 1 and 1.25) were prepared by laser cladding. X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and scanning electron microscopy (SEM) were used to characterize the phase and crystal structure. The mechanical properties were tested. The results show that Ti is solidly dissolved in the FCC phase for solid solution strengthening. Mo is precipitated as the second phase σ phase for second phase dispersion strengthening. As x increases, the coating becomes the FCC+σ phase, and the σ phase disappears at x = 1.25. The microhardness and wear resistance of the coating are greatly improved by solution strengthening and second phase precipitation strengthening. The microhardness is up to 3.18 times of the substrate, and the wear resistance is up to 10.9 times of the substrate. Corrosion resistance of all coatings is better than that of 45# steel. With the increase of x, the corrosion resistance of the coating increases first and then decreases. When x = 1, the corrosion resistance of the coating is the best.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108509"},"PeriodicalIF":4.3,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323310","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}
High entropy alloys have been regarded as a promising material for wear-resistant coating application. However, the efficient production of high entropy alloy coatings (HEACs) remains an obstacle for their industrial implementation. In this study, the CoCrFeNiMo HEACs with the thickness of ∼4 mm and robust metallurgical bonding were successfully manufactured on the Q345 steel substrate through the plasma transferred arc welding (PTAW) technique. The influence of the varying PTAW arc current (130 A, 180 A, and 230 A) on the microstructure, tribology behavior and wear-resistance of CoCrFeNiMo HEACs was systematically investigated. With the increasing arc current, along with the higher dilution rate, the content of Fe in PTAW-coatings apparently increases from 21.07 at. % (130 A) to 47.60 at. % (180 A), and finally to 55.76 at. % (230 A). The microstructure of PTAW-coatings consists of the primary phase (dendritic region) and the /FCC dual-phases eutectic (inter-dendritic region). However, the primary phase gradually changes from to FCC phase with the increasing PTAW arc current. Nanoindentation test shows that the hardness of σ-phase, σ/FCC eutectics and FCC phase are 19.91 GPa, 10.71 GPa and 5.34 GPa, respectively. The dry sliding friction and wear tests indicate the improved wear-resistance as the PTAW arc current decreases from 230 A to 130 A. The coefficient of friction (COF) decreases from 0.75 to 0.64, the average hardness increases from 316 HV to 661 HV, and the wear rate reduces from 5.65 10−4 mm3 Nm−1 to 2.42 10−4 mm3 Nm−1. Meanwhile, the wear mechanism gradually changes from a combination of adhesive wear, oxidative wear and abrasive wear to the dominant abrasive wear due to the changed constituent phases.
{"title":"Microstructure and wear-resistance of the CoCrFeNiMo high entropy alloy coatings by modulated arc currents using plasma transferred arc weld technique","authors":"Ziheng Liu, Gang Liu, Xinlei Miao, Liyang Sun, Zhenhua Han, Guojun Zhang","doi":"10.1016/j.intermet.2024.108506","DOIUrl":"10.1016/j.intermet.2024.108506","url":null,"abstract":"<div><div>High entropy alloys have been regarded as a promising material for wear-resistant coating application. However, the efficient production of high entropy alloy coatings (HEACs) remains an obstacle for their industrial implementation. In this study, the CoCrFeNiMo HEACs with the thickness of ∼4 mm and robust metallurgical bonding were successfully manufactured on the Q345 steel substrate through the plasma transferred arc welding (PTAW) technique. The influence of the varying PTAW arc current (130 A, 180 A, and 230 A) on the microstructure, tribology behavior and wear-resistance of CoCrFeNiMo HEACs was systematically investigated. With the increasing arc current, along with the higher dilution rate, the content of Fe in PTAW-coatings apparently increases from 21.07 at. % (130 A) to 47.60 at. % (180 A), and finally to 55.76 at. % (230 A). The microstructure of PTAW-coatings consists of the primary phase (dendritic region) and the <span><math><mrow><mi>σ</mi></mrow></math></span>/FCC dual-phases eutectic (inter-dendritic region). However, the primary phase gradually changes from <span><math><mrow><mi>σ</mi></mrow></math></span> to FCC phase with the increasing PTAW arc current. Nanoindentation test shows that the hardness of σ-phase, σ/FCC eutectics and FCC phase are 19.91 GPa, 10.71 GPa and 5.34 GPa, respectively. The dry sliding friction and wear tests indicate the improved wear-resistance as the PTAW arc current decreases from 230 A to 130 A. The coefficient of friction (COF) decreases from 0.75 to 0.64, the average hardness increases from 316 HV to 661 HV, and the wear rate reduces from 5.65 <span><math><mrow><mo>×</mo></mrow></math></span> 10<sup>−4</sup> mm<sup>3</sup> <span><math><mrow><mo>∙</mo></mrow></math></span> Nm<sup>−1</sup> to 2.42 <span><math><mrow><mo>×</mo></mrow></math></span> 10<sup>−4</sup> mm<sup>3</sup> <span><math><mrow><mo>∙</mo></mrow></math></span> Nm<sup>−1</sup>. Meanwhile, the wear mechanism gradually changes from a combination of adhesive wear, oxidative wear and abrasive wear to the dominant abrasive wear due to the changed constituent phases.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108506"},"PeriodicalIF":4.3,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314918","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 : 2024-09-22DOI: 10.1016/j.intermet.2024.108500
Kaiju Lu, Jarir Aktaa
We report the short-term tensile creep behavior of CoCrFeMnNi and CoCrNi model MPEAs at 550 °C. Dislocation glide and dislocation-dislocation/lattice interactions are proposed to be dominated deformation mechanisms for CoCrFeMnNi and CoCrNi, respectively. Besides, compared to CoCrFeMnNi, CoCrNi exhibits lower creep rate and longer rupture time at same testing conditions. This is attributed to CoCrNi's lower stacking fault energy and higher lattice friction. Additionally, the effect of grain size on the short-term creep behavior of CoCrFeMnNi was revealed.
{"title":"Short-term tensile creep behavior of CoCrNi-based multi-principal element alloys","authors":"Kaiju Lu, Jarir Aktaa","doi":"10.1016/j.intermet.2024.108500","DOIUrl":"10.1016/j.intermet.2024.108500","url":null,"abstract":"<div><div>We report the short-term tensile creep behavior of CoCrFeMnNi and CoCrNi model MPEAs at 550 °C. Dislocation glide and dislocation-dislocation/lattice interactions are proposed to be dominated deformation mechanisms for CoCrFeMnNi and CoCrNi, respectively. Besides, compared to CoCrFeMnNi, CoCrNi exhibits lower creep rate and longer rupture time at same testing conditions. This is attributed to CoCrNi's lower stacking fault energy and higher lattice friction. Additionally, the effect of grain size on the short-term creep behavior of CoCrFeMnNi was revealed.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108500"},"PeriodicalIF":4.3,"publicationDate":"2024-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0966979524003194/pdfft?md5=94076ce94cd3ec7477ea8e3f4f65e41c&pid=1-s2.0-S0966979524003194-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142313011","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 : 2024-09-21DOI: 10.1016/j.intermet.2024.108499
Jianfei Peng , Shuaijie Yuan , Wanlin Wang , Peiyuan Gan , Junyu Ji , Jie Zeng
The modified homogenization process has garnered increasing interest in the high-alloyed materials preparation owing to its effectiveness in mitigating segregation and enhancing properties. In this work, the effects of homogenization treatment on the intermetallic phases, solidification structure and mechanical properties of a novel Al-Zn-Mg-Cu-Y alloy are investigated. The results indicate that the Al8Cu4Y phase is formed in the matrix and maintains steady during homogenization. It is confirmed that lower homogenization temperature (400 °C) can promote Al3Zr nucleation, while higher temperature (460 °C) can accelerate the dissolution of MgZn2 phase owing to a higher diffusion coefficient. Compared with single homogenization treatment, a two-stage homogenization (400 °C/16 h + 460 °C/24 h) can achieve a combination result of massive MgZn2 phases dissolution and fine Al3Zr dispersoids precipitation in the alloy. Moreover, the mean grain size ranges from 166.1 to 154.5 μm and its misorientation angle ranges from 39.9 to 40.9° during homogenization, suggesting a certain thermal stability for Al-Zn-Mg-Cu-Y alloy. In addition, Vickers hardness and electrical conductivity show a linear relation with the Zn, Mg and Cu elemental content in the matrix. The alloy demonstrates an improved tensile strength after homogenization, which is mainly related to MgZn2 dissolution and Al3Zr precipitation.
{"title":"Tailoring intermetallic phase and mechanical property improvement in a novel Al-Zn-Mg-Cu-Y alloy via homogenization treatment","authors":"Jianfei Peng , Shuaijie Yuan , Wanlin Wang , Peiyuan Gan , Junyu Ji , Jie Zeng","doi":"10.1016/j.intermet.2024.108499","DOIUrl":"10.1016/j.intermet.2024.108499","url":null,"abstract":"<div><p>The modified homogenization process has garnered increasing interest in the high-alloyed materials preparation owing to its effectiveness in mitigating segregation and enhancing properties. In this work, the effects of homogenization treatment on the intermetallic phases, solidification structure and mechanical properties of a novel Al-Zn-Mg-Cu-Y alloy are investigated. The results indicate that the Al<sub>8</sub>Cu<sub>4</sub>Y phase is formed in the matrix and maintains steady during homogenization. It is confirmed that lower homogenization temperature (400 °C) can promote Al<sub>3</sub>Zr nucleation, while higher temperature (460 °C) can accelerate the dissolution of MgZn<sub>2</sub> phase owing to a higher diffusion coefficient. Compared with single homogenization treatment, a two-stage homogenization (400 °C/16 h + 460 °C/24 h) can achieve a combination result of massive MgZn<sub>2</sub> phases dissolution and fine Al<sub>3</sub>Zr dispersoids precipitation in the alloy. Moreover, the mean grain size ranges from 166.1 to 154.5 μm and its misorientation angle ranges from 39.9 to 40.9° during homogenization, suggesting a certain thermal stability for Al-Zn-Mg-Cu-Y alloy. In addition, Vickers hardness and electrical conductivity show a linear relation with the Zn, Mg and Cu elemental content in the matrix. The alloy demonstrates an improved tensile strength after homogenization, which is mainly related to MgZn<sub>2</sub> dissolution and Al<sub>3</sub>Zr precipitation.</p></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108499"},"PeriodicalIF":4.3,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272722","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 : 2024-09-20DOI: 10.1016/j.intermet.2024.108505
Yu Ji , Hongwei Zhang , Jingyu Pang , Zhenqiang Xing , Long Zhang , Zhengwang Zhu , Aimin Wang , Haifeng Zhang
The work developed a series of novel Co-free high-entropy alloys (HEAs), i.e. Fe3.75Cr1.25NiAl0.6-xTix (x = 0, 0.15, 0.30 and 0.40, molar ratio) HEAs abbreviated as Ti0, Ti0.15, Ti0.30 and Ti0.40, respectively. The effects of Ti/Al ratio (Al partially replaced by Ti) on the microstructure and tensile properties were investigated systematically. The Ti0 HEA contains the FCC phase in dendritic regions and the BCC and B2 phases (BCC/B2) in interdendritic regions. Moreover, the spherical ordered B2 nanoparticles are embedded in the BCC matrix. With increasing the Ti/Al ratio from 0 to 1/3, there is a phase transition from B2-NiAl to L21-Ni2AlTi. Furthermore, the morphology of the nanoparticles evolves from spherical to cuboidal. With further increasing the Ti/Al ratio from 1/3 to 1 and 2, the morphology of nanoparticles evolves from cuboidal back to spherical. In addition, the Ti0.40 HEA has σ phases besides FCC, BCC, and L21 phases. The analysis of tensile properties shows that properly adjusting Ti/Al ratios sharply improves the plasticity and slightly improves the ultimate strength, but only causes a limited decrease in the yield strength. Specifically, the Ti0.15 HEA has a superior combination of strength and plasticity, exhibiting a yield strength of 819 MPa, an ultimate strength of 1113 MPa, and a fracture strain of 13.4 %. The SRO, the solid-solution strengthening, the phase transformation, and the shape of nanoparticles were discussed in detail, which reveals the origins of the excellent tensile properties. In addition, the excessive addition of Ti forms the σ phase, leading to a serious brittleness.
These findings are believed to promote the development of low-cost HEAs with BCC/L21 for practical applications.
{"title":"The effect of Ti/Al ratios on the evolution of precipitates and their effects on tensile properties for Fe3.75Cr1.25NiAl0.6-xTix high entropy alloys","authors":"Yu Ji , Hongwei Zhang , Jingyu Pang , Zhenqiang Xing , Long Zhang , Zhengwang Zhu , Aimin Wang , Haifeng Zhang","doi":"10.1016/j.intermet.2024.108505","DOIUrl":"10.1016/j.intermet.2024.108505","url":null,"abstract":"<div><p>The work developed a series of novel Co-free high-entropy alloys (HEAs), i.e. Fe<sub>3.75</sub>Cr<sub>1.25</sub>NiAl<sub>0.6-<em>x</em></sub>Ti<sub><em>x</em></sub> (<em>x</em> = 0, 0.15, 0.30 and 0.40, molar ratio) HEAs abbreviated as Ti0, Ti0.15, Ti0.30 and Ti0.40, respectively. The effects of Ti/Al ratio (Al partially replaced by Ti) on the microstructure and tensile properties were investigated systematically. The Ti0 HEA contains the FCC phase in dendritic regions and the BCC and B2 phases (BCC/B2) in interdendritic regions. Moreover, the spherical ordered B2 nanoparticles are embedded in the BCC matrix. With increasing the Ti/Al ratio from 0 to 1/3, there is a phase transition from B2-NiAl to L2<sub>1</sub>-Ni<sub>2</sub>AlTi. Furthermore, the morphology of the nanoparticles evolves from spherical to cuboidal. With further increasing the Ti/Al ratio from 1/3 to 1 and 2, the morphology of nanoparticles evolves from cuboidal back to spherical. In addition, the Ti0.40 HEA has <em>σ</em> phases besides FCC, BCC, and L2<sub>1</sub> phases. The analysis of tensile properties shows that properly adjusting Ti/Al ratios sharply improves the plasticity and slightly improves the ultimate strength, but only causes a limited decrease in the yield strength. Specifically, the Ti0.15 HEA has a superior combination of strength and plasticity, exhibiting a yield strength of 819 MPa, an ultimate strength of 1113 MPa, and a fracture strain of 13.4 %. The SRO, the solid-solution strengthening, the phase transformation, and the shape of nanoparticles were discussed in detail, which reveals the origins of the excellent tensile properties. In addition, the excessive addition of Ti forms the <em>σ</em> phase, leading to a serious brittleness.</p><p>These findings are believed to promote the development of low-cost HEAs with BCC/L2<sub>1</sub> for practical applications.</p></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108505"},"PeriodicalIF":4.3,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272721","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 : 2024-09-20DOI: 10.1016/j.intermet.2024.108497
Qi Wei , Aijun Zhang , Benbin Xin , Jiesheng Han , Bo Su , Xiaochao Wang , Junhu Meng
VNbTa refractory medium-entropy alloy (RMEA) with extraordinary strength-ductility synergy and rolling formability was deemed as an ideal structural material suitable for industrial applications, whereas the tribological performance has been still unclear. Therefore, this work employed a ball-on-disc tribometer to evaluate friction and wear properties of VNbTa alloy at various temperatures. It was surprisingly found that, at 800 °C, the alloy exhibits exceptional tribological performance with the coefficient of friction (COF) of 0.13 and wear rate of 3.9 × 10−6 mm3/Nm. Our results indicated that the mild friction and wear at 800 °C are mainly attributed to the durable lubrication of in-situ molten V2O5 as well as good load-bearing capacity of hard oxide scale.
{"title":"Observation of low friction and high wear resistance in the ductile VNbTa refractory medium-entropy alloy at 800 °C","authors":"Qi Wei , Aijun Zhang , Benbin Xin , Jiesheng Han , Bo Su , Xiaochao Wang , Junhu Meng","doi":"10.1016/j.intermet.2024.108497","DOIUrl":"10.1016/j.intermet.2024.108497","url":null,"abstract":"<div><p>VNbTa refractory medium-entropy alloy (RMEA) with extraordinary strength-ductility synergy and rolling formability was deemed as an ideal structural material suitable for industrial applications, whereas the tribological performance has been still unclear. Therefore, this work employed a ball-on-disc tribometer to evaluate friction and wear properties of VNbTa alloy at various temperatures. It was surprisingly found that, at 800 °C, the alloy exhibits exceptional tribological performance with the coefficient of friction (COF) of 0.13 and wear rate of 3.9 × 10<sup>−6</sup> mm<sup>3</sup>/Nm. Our results indicated that the mild friction and wear at 800 °C are mainly attributed to the durable lubrication of in-situ molten V<sub>2</sub>O<sub>5</sub> as well as good load-bearing capacity of hard oxide scale.</p></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108497"},"PeriodicalIF":4.3,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272758","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 : 2024-09-20DOI: 10.1016/j.intermet.2024.108479
Christoph Stangl , Eva Kollmannsberger , Manja Krüger , Otto Huber , Hubert Klaus , Holger Saage
The susceptibility of titanium aluminides (TiAl) to environmental embrittlement is one of the factors limiting the use of this class of intermetallic alloys. After being exposed to air at high temperatures, the ductility of the material at room temperature is significantly reduced or even completely lost. In the present work the influence of near surface grain refinement on the example of the β-stabilised TNM alloy on the embrittlement behaviour after exposure for 2 h at 700 °C in air is presented and discussed. The main characteristic of the environmental embrittlement is that cracks during tensile tests at room temperature appear on the surface and lead to rapid failure. One of the reasons given in literature for this behaviour is that high tensile stresses form at the sample edge by exposure. Grain refinement of the surface region with a depth of approximately 350 μm displaces crack initiation during tensile testing well below the surface after exposure. The environmental embrittlement phenomenon after short-term exposure does, thus, not occur in this layer-like structure. Various reasons for this behaviour, which include delayed crack formation, stress relaxation during loading and cooling after loading as well as supporting effects, but also the limitations of the treatment method, are discussed in the work.
{"title":"Reducing the environmental embrittlement effect of TiAl alloys exposed to air at high temperatures by a fine-grained surface structure","authors":"Christoph Stangl , Eva Kollmannsberger , Manja Krüger , Otto Huber , Hubert Klaus , Holger Saage","doi":"10.1016/j.intermet.2024.108479","DOIUrl":"10.1016/j.intermet.2024.108479","url":null,"abstract":"<div><p>The susceptibility of titanium aluminides (TiAl) to environmental embrittlement is one of the factors limiting the use of this class of intermetallic alloys. After being exposed to air at high temperatures, the ductility of the material at room temperature is significantly reduced or even completely lost. In the present work the influence of near surface grain refinement on the example of the β-stabilised TNM alloy on the embrittlement behaviour after exposure for 2 h at 700 °C in air is presented and discussed. The main characteristic of the environmental embrittlement is that cracks during tensile tests at room temperature appear on the surface and lead to rapid failure. One of the reasons given in literature for this behaviour is that high tensile stresses form at the sample edge by exposure. Grain refinement of the surface region with a depth of approximately 350 μm displaces crack initiation during tensile testing well below the surface after exposure. The environmental embrittlement phenomenon after short-term exposure does, thus, not occur in this layer-like structure. Various reasons for this behaviour, which include delayed crack formation, stress relaxation during loading and cooling after loading as well as supporting effects, but also the limitations of the treatment method, are discussed in the work.</p></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108479"},"PeriodicalIF":4.3,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S096697952400298X/pdfft?md5=948513714c12dcfdbe04887ae1459712&pid=1-s2.0-S096697952400298X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272756","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 : 2024-09-19DOI: 10.1016/j.intermet.2024.108503
Lihua Fu , Meng Zhou , Yuanan Gao , Bin Gan , Sanming Du , Yongzhen Zhang , Chenfei Song , Lvdong Hua , Guofeng Zhang
In this study, Cr3C2/Ni3Al composites containing Cr3C2 particles of different sizes were prepared via hot-press sintering. Subsequently, the effects of the size of the added Cr3C2 particles on the microstructure, hardness, and tribological properties of the Cr3C2/Ni3Al composites were investigated. The results showed that the Ni3Al powder and Cr3C2 particles in the composites exhibited obvious interdiffusion interactions during the hot-press sintering process and formed a new diffusion phase with an M7C3 (M = Cr, Fe, and Ni) structure in the Cr3C2/Ni3Al composites. In addition, the diffusion effect in the composites with small Cr3C2 particles was full, the proportion of the M7C3 (M = Cr, Fe, and Ni) diffusion phase in the composites was greater, and the solid-solution strengthening effect of the matrix phase was evident. The hardness of the Cr3C2/Ni3Al composites was noticeably higher than that of the Ni3Al alloy because of the combination of particle, solid-solution, and refined crystalline strengthening effects. The composite with 5 μm Cr3C2 particles displayed the maximum hardness (56.3 HRC) and best wear resistance. The wear mechanism results indicated that the carbide particles in the composites improved the hardness, carried the load, and blocked the movement of abrasive particles, effectively protecting the matrix from wear. However, when the added Cr3C2 particles were too large, the weak interfacial bond between the chromium carbides and the matrix phases in the composites allowed the chromium carbides to easily crack and fall off, which decreased the wear resistance.
{"title":"Microstructure, hardness, and wear properties of hot-press sintered Cr3C2/Ni3Al composites containing Cr3C2 particles of different sizes","authors":"Lihua Fu , Meng Zhou , Yuanan Gao , Bin Gan , Sanming Du , Yongzhen Zhang , Chenfei Song , Lvdong Hua , Guofeng Zhang","doi":"10.1016/j.intermet.2024.108503","DOIUrl":"10.1016/j.intermet.2024.108503","url":null,"abstract":"<div><p>In this study, Cr<sub>3</sub>C<sub>2</sub>/Ni<sub>3</sub>Al composites containing Cr<sub>3</sub>C<sub>2</sub> particles of different sizes were prepared via hot-press sintering. Subsequently, the effects of the size of the added Cr<sub>3</sub>C<sub>2</sub> particles on the microstructure, hardness, and tribological properties of the Cr<sub>3</sub>C<sub>2</sub>/Ni<sub>3</sub>Al composites were investigated. The results showed that the Ni<sub>3</sub>Al powder and Cr<sub>3</sub>C<sub>2</sub> particles in the composites exhibited obvious interdiffusion interactions during the hot-press sintering process and formed a new diffusion phase with an M<sub>7</sub>C<sub>3</sub> (M = Cr, Fe, and Ni) structure in the Cr<sub>3</sub>C<sub>2</sub>/Ni<sub>3</sub>Al composites. In addition, the diffusion effect in the composites with small Cr<sub>3</sub>C<sub>2</sub> particles was full, the proportion of the M<sub>7</sub>C<sub>3</sub> (M = Cr, Fe, and Ni) diffusion phase in the composites was greater, and the solid-solution strengthening effect of the matrix phase was evident. The hardness of the Cr<sub>3</sub>C<sub>2</sub>/Ni<sub>3</sub>Al composites was noticeably higher than that of the Ni<sub>3</sub>Al alloy because of the combination of particle, solid-solution, and refined crystalline strengthening effects. The composite with 5 μm Cr<sub>3</sub>C<sub>2</sub> particles displayed the maximum hardness (56.3 HRC) and best wear resistance. The wear mechanism results indicated that the carbide particles in the composites improved the hardness, carried the load, and blocked the movement of abrasive particles, effectively protecting the matrix from wear. However, when the added Cr<sub>3</sub>C<sub>2</sub> particles were too large, the weak interfacial bond between the chromium carbides and the matrix phases in the composites allowed the chromium carbides to easily crack and fall off, which decreased the wear resistance.</p></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108503"},"PeriodicalIF":4.3,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272757","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号