Pub Date : 2024-12-01DOI: 10.1016/j.intermet.2024.108587
Yuexing Wang , Xiangou Zhang , Linwei Cao , Xiangyu Sun
The growth of intermetallic compounds (IMC) at the interface of solder joints in microelectronic packaging is one of the most critical factors affecting the long-term reliability. Traditional studies have shown that IMCs growth curves follow a power-law relationship with an exponent of 1/2 or 1/3 approximately. However, limited research has been conducted to validate the effectiveness of this formula in predicting IMCs growth. Consequently, we investigated the growth kinetics of IMCs under ultra-long-term isothermal aging conditions. Our findings revealed that the power-law formulas derived from fitting failed to accurately predict the subsequent growth of IMCs beyond the fitting process. This inadequacy was attributed to the initial consideration of the IMCs growth rate as infinite. To address this issue, an improved kinetic growth model of interfacial IMCs layer based on ordinary differential equation modeling is proposed. The effectiveness of the proposed model was validated through experiments conducted by ourselves and other researchers, demonstrating significantly improved accuracy in predicting the growth kinetics of IMCs compared to the traditional approach.
{"title":"The inadequacy of the traditional power law formula in predicting the growth kinetics of intermetallic compounds at the interface of solder joints in microelectronic packaging","authors":"Yuexing Wang , Xiangou Zhang , Linwei Cao , Xiangyu Sun","doi":"10.1016/j.intermet.2024.108587","DOIUrl":"10.1016/j.intermet.2024.108587","url":null,"abstract":"<div><div>The growth of intermetallic compounds (IMC) at the interface of solder joints in microelectronic packaging is one of the most critical factors affecting the long-term reliability. Traditional studies have shown that IMCs growth curves follow a power-law relationship with an exponent of 1/2 or 1/3 approximately. However, limited research has been conducted to validate the effectiveness of this formula in predicting IMCs growth. Consequently, we investigated the growth kinetics of IMCs under ultra-long-term isothermal aging conditions. Our findings revealed that the power-law formulas derived from fitting failed to accurately predict the subsequent growth of IMCs beyond the fitting process. This inadequacy was attributed to the initial consideration of the IMCs growth rate as infinite. To address this issue, an improved kinetic growth model of interfacial IMCs layer based on ordinary differential equation modeling is proposed. The effectiveness of the proposed model was validated through experiments conducted by ourselves and other researchers, demonstrating significantly improved accuracy in predicting the growth kinetics of IMCs compared to the traditional approach.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"176 ","pages":"Article 108587"},"PeriodicalIF":4.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756733","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 : 2024-11-30DOI: 10.1016/j.intermet.2024.108581
Yulin Ma , Xinyu Wang , Zhuang Li , Junjia Zhang , Jun Zhang
FeCoNiCrAl high-entropy alloy (HEA) coatings have here been prepared on Q235 steel by using the plasma spraying technology. The effects of heat treatment (300 °C, 400 °C, and 500 °C) on the coating phase, surface and cross section morphologies, surface Brinell hardness (HRB), cross section Vickers hardness (HV), and element diffusion at the coating interface, were then investigated. The distribution of pores, cracks, and unmelted particles on the surface of the coating was analyzed by scanning electron microscopy (SEM). The results showed that the BCC crystalline structure of the HEA coating did not change significantly after heat treatment at 300 °C, 400 °C, and 500 °C. In addition, the bonding between the coating and the matrix interface became significantly improved, and the cracks at the coating interface were eliminated. New oxides that filled the pores and cracks inside and at the interface of the coating were also observed as the temperature and holding time increased. Furthermore, the surface hardness of the Q235 steel was reduced as a result of the spray coating. However, this surface hardness was increased to HRB 85 (or even more) after heat treatment. Compared with the other samples, the coating sample that was heat-treated at 500 °C showed the best strength.
{"title":"Effect of heat treatment on the interfacial element diffusion and hardness of FeCoNiCrAl high-entropy alloy coatings","authors":"Yulin Ma , Xinyu Wang , Zhuang Li , Junjia Zhang , Jun Zhang","doi":"10.1016/j.intermet.2024.108581","DOIUrl":"10.1016/j.intermet.2024.108581","url":null,"abstract":"<div><div>FeCoNiCrAl high-entropy alloy (HEA) coatings have here been prepared on Q235 steel by using the plasma spraying technology. The effects of heat treatment (300 °C, 400 °C, and 500 °C) on the coating phase, surface and cross section morphologies, surface Brinell hardness (HRB), cross section Vickers hardness (HV), and element diffusion at the coating interface, were then investigated. The distribution of pores, cracks, and unmelted particles on the surface of the coating was analyzed by scanning electron microscopy (SEM). The results showed that the BCC crystalline structure of the HEA coating did not change significantly after heat treatment at 300 °C, 400 °C, and 500 °C. In addition, the bonding between the coating and the matrix interface became significantly improved, and the cracks at the coating interface were eliminated. New oxides that filled the pores and cracks inside and at the interface of the coating were also observed as the temperature and holding time increased. Furthermore, the surface hardness of the Q235 steel was reduced as a result of the spray coating. However, this surface hardness was increased to HRB 85 (or even more) after heat treatment. Compared with the other samples, the coating sample that was heat-treated at 500 °C showed the best strength.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"176 ","pages":"Article 108581"},"PeriodicalIF":4.3,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744214","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}
The interfacial bonding and mechanical properties of a TC1/1060/6061/1060/TC1 explosively welded composite pipe were investigated in this work. The interface morphology, grain morphology, and element diffusion of the composite pipe were analyzed using electron microscopy, electron backscatter diffraction, energy dispersive spectroscopy, and X-ray diffraction. The results showed that the microstructure of the inner and outer TC1 welds transformed from coarse β grains to martensitic α′ phase, thus improving the hardness, wear resistance, and toughness of the base metal. The TC1/1060 interface weld exhibited an evident and appropriate width diffusion area, and direct bonding occurred at the TC1/1060 interface. and there was no intermetallic compound at the interface, indicating that the composite pipe had a good bonding quality. The micro- and macro-mechanical properties of the composite pipe were analyzed by performing a microhardness test, tensile test, and tensile shear test. The results showed that the welds of each layer had little effect on the macro-mechanical properties of the material but significantly influenced the overall ductility of the composite pipe material. The composite pipe material exhibited a layered failure form when subjected to tensile fracture, which imparted it with a better ductility. Because delamination damage starts from the welds of each layer, the overlap and closeness of the welds of each layer should be avoided when applying the proposed method in the preparation of composite pipes.
{"title":"Interface bonding and mechanical properties of large explosively welded titanium/aluminum composite pipes","authors":"Haiwei Zhou, Fei Shao, Linyue Bai, Jiaxin Yuan, Qian Xu, Hailong Liu","doi":"10.1016/j.intermet.2024.108476","DOIUrl":"10.1016/j.intermet.2024.108476","url":null,"abstract":"<div><div>The interfacial bonding and mechanical properties of a TC1/1060/6061/1060/TC1 explosively welded composite pipe were investigated in this work. The interface morphology, grain morphology, and element diffusion of the composite pipe were analyzed using electron microscopy, electron backscatter diffraction, energy dispersive spectroscopy, and X-ray diffraction. The results showed that the microstructure of the inner and outer TC1 welds transformed from coarse β grains to martensitic α′ phase, thus improving the hardness, wear resistance, and toughness of the base metal. The TC1/1060 interface weld exhibited an evident and appropriate width diffusion area, and direct bonding occurred at the TC1/1060 interface. and there was no intermetallic compound at the interface, indicating that the composite pipe had a good bonding quality. The micro- and macro-mechanical properties of the composite pipe were analyzed by performing a microhardness test, tensile test, and tensile shear test. The results showed that the welds of each layer had little effect on the macro-mechanical properties of the material but significantly influenced the overall ductility of the composite pipe material. The composite pipe material exhibited a layered failure form when subjected to tensile fracture, which imparted it with a better ductility. Because delamination damage starts from the welds of each layer, the overlap and closeness of the welds of each layer should be avoided when applying the proposed method in the preparation of composite pipes.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"176 ","pages":"Article 108476"},"PeriodicalIF":4.3,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744144","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 : 2024-11-29DOI: 10.1016/j.intermet.2024.108582
Xiaoyu Sun , Xiaolong Li , Sheng Guo , Lilong Zhu , Jianwei Teng , Liang Jiang , Johan Moverare , Xin-Hai Li , Ru Lin Peng
Y/Hf-doped AlCoCrFeNi high-entropy alloys stand out for their potential application in high temperature coatings. Thereinto, both Cr and Al are crucial for improving oxidation properties. However, simultaneously increasing the content of Al and Cr is not advisable, since it can significantly reduce the ductility/toughness of the coating. In this research, we proposed an equivalent replacement method of Al and Cr, namely, tuning Al/Cr ratio (ACR), to enhance the elevated-temperature oxidation resistance of AlCoCrFeNi alloys. This strategy was verified by the 1000 h/1100 °C oxidation tests of three Y-doped AlCoCrFeNi alloys with different ACRs of 0.78, 0.58 and 0.41. The test results indicated an elusive transformation of oxidation rate occurred on these alloys, that the alloy with lowest ACR exhibited an initially higher oxidation rate but a lower oxidation rate over an extended period, in comparison to those higher ACR alloys. The underlying oxidation mechanisms were uncovered using microscopic techniques and thermodynamics calculations. The initial higher oxidation rate was ascribed to the rapid growth of spinel oxides, while the extended slower oxidation process was attributed to the resulting Al2O3 scale with larger grain sizes. Thermodynamic assessment revealed that larger Al2O3 grains corresponding to fewer grain boundaries decreased the diffusion coefficient of oxygen in Al2O3 scale. Our research is of both theoretical and industrial importance for clarifying the high temperature oxidation mechanism of Y-doped AlCoCrFeNi alloys and enhancing the oxidation resistance in multicomponent alloy systems.
{"title":"The impact of Al/Cr ratio on the oxidation kinetics of Y-doped AlCoCrFeNi high-entropy alloys at 1100 °C","authors":"Xiaoyu Sun , Xiaolong Li , Sheng Guo , Lilong Zhu , Jianwei Teng , Liang Jiang , Johan Moverare , Xin-Hai Li , Ru Lin Peng","doi":"10.1016/j.intermet.2024.108582","DOIUrl":"10.1016/j.intermet.2024.108582","url":null,"abstract":"<div><div>Y/Hf-doped AlCoCrFeNi high-entropy alloys stand out for their potential application in high temperature coatings. Thereinto, both Cr and Al are crucial for improving oxidation properties. However, simultaneously increasing the content of Al and Cr is not advisable, since it can significantly reduce the ductility/toughness of the coating. In this research, we proposed an equivalent replacement method of Al and Cr, namely, tuning Al/Cr ratio (ACR), to enhance the elevated-temperature oxidation resistance of AlCoCrFeNi alloys. This strategy was verified by the 1000 h/1100 °C oxidation tests of three Y-doped AlCoCrFeNi alloys with different ACRs of 0.78, 0.58 and 0.41. The test results indicated an elusive transformation of oxidation rate occurred on these alloys, that the alloy with lowest ACR exhibited an initially higher oxidation rate but a lower oxidation rate over an extended period, in comparison to those higher ACR alloys. The underlying oxidation mechanisms were uncovered using microscopic techniques and thermodynamics calculations. The initial higher oxidation rate was ascribed to the rapid growth of spinel oxides, while the extended slower oxidation process was attributed to the resulting Al<sub>2</sub>O<sub>3</sub> scale with larger grain sizes. Thermodynamic assessment revealed that larger Al<sub>2</sub>O<sub>3</sub> grains corresponding to fewer grain boundaries decreased the diffusion coefficient of oxygen in Al<sub>2</sub>O<sub>3</sub> scale. Our research is of both theoretical and industrial importance for clarifying the high temperature oxidation mechanism of Y-doped AlCoCrFeNi alloys and enhancing the oxidation resistance in multicomponent alloy systems.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"176 ","pages":"Article 108582"},"PeriodicalIF":4.3,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744142","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 : 2024-11-29DOI: 10.1016/j.intermet.2024.108579
Huiqin Wang , Bin Tang , Yudong Chu , Xiaofei Chen , Yilei Wang , Biao Ma , Jinshan Li
For TiAl alloys, forging in the α single-phase region is an important and efficient method to obtain fine lamellar structure. In this study, Ti-46.5Al-4Nb-1.8Cr-0.2Ta (at.%) alloy was fabricated using direct single-pass forging near α transition temperature (α-DSPF), the microstructure evolution and mechanical properties were investigated. The results show that the refined near lamellar structures were obtained by means of recrystallization of α phase through near-isothermal forging at 1390 °C. Finally, the yield strength, ultimate tensile strength and elongation of the as-forged alloy at 1390 °C were simultaneously improved due to the improvement of lamellar fraction, refinement of grain size and reduction of the βo phase. This work provides a promising and cost-effective method for α-processing of TiAl alloys to improve the mechanical properties.
{"title":"Microstructure evolution and mechanical properties of Ti-46.5Al-4Nb-1Cr-0.2Ta alloy during near-isothermal forging at α single-phase region","authors":"Huiqin Wang , Bin Tang , Yudong Chu , Xiaofei Chen , Yilei Wang , Biao Ma , Jinshan Li","doi":"10.1016/j.intermet.2024.108579","DOIUrl":"10.1016/j.intermet.2024.108579","url":null,"abstract":"<div><div>For TiAl alloys, forging in the α single-phase region is an important and efficient method to obtain fine lamellar structure. In this study, Ti-46.5Al-4Nb-1.8Cr-0.2Ta (at.%) alloy was fabricated using direct single-pass forging near α transition temperature (α-DSPF), the microstructure evolution and mechanical properties were investigated. The results show that the refined near lamellar structures were obtained by means of recrystallization of α phase through near-isothermal forging at 1390 °C. Finally, the yield strength, ultimate tensile strength and elongation of the as-forged alloy at 1390 °C were simultaneously improved due to the improvement of lamellar fraction, refinement of grain size and reduction of the β<sub>o</sub> phase. This work provides a promising and cost-effective method for α-processing of TiAl alloys to improve the mechanical properties.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"176 ","pages":"Article 108579"},"PeriodicalIF":4.3,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744143","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}
A novel AlCoCrFeNi2.1 high-entropy alloy self-lubricating coating was prepared by multilayer graphene (MLG) enhancement. The AlCoCrFeNi2.1-MLG (3 wt%) high-entropy alloy self-lubricating coating was prepared on AISI1045 steel using laser cladding by introducing lubricant named MLG. The microstructure, phase structure, wear resistance and corrosion performance of the AlCoCrFeNi2.1-MLG coating were studied. It is shown that the microstructure of the AlCoCrFeNi2.1-MLG coating has typical dendritic (DR) and interdendritic (ID) structures, with the dendrites consisting of high density M23C6 phase precipitation and FCC phase distributed in the interdendritic region. With the addition of MLG, the average hardness of the AlCoCrFeNi2.1 coating increases from 306.71 HV to 486.68 HV (an increase of 58.68 %). The average coefficient of friction decreases from 0.59 to 0.48 (a reduction of 22.92 %). The wear rate decreases from 1.678 × 10- 6 mm3·N− 1 m−1 to 0.825 × 10- 6 mm3·N− 1 m− 1 (a reduction of 50.83 %). This is due to the formation of a lubricant film in the AlCoCrFeNi2.1-MLG coating. The wear mechanism changes from plastic deformation and abrasive debris wear to slight delamination and spalling of the lubricant film. However, the corrosion performance of the AlCoCrFeNi2.1-MLG coating is slightly reduced by the occurrence of micro-electro-coupling corrosion on the corroded surface. The M23C6 phase is used as the anode and the FCC phase is used as the cathode. The subsequent generation of a passivation film prevents the appearance of severe electro-coupling corrosion. The wear resistance of the AlCoCrFeNi2.1-MLG coating is substantially improved while taking into account the corrosion performance. This study provides important values for laser cladding of self-lubricating composite coatings of high-entropy alloys.
{"title":"Microstructure and wear resistance of multi-layer graphene doped AlCoCrFeNi2.1 high-entropy alloy self-lubricating coating prepared by laser cladding","authors":"Jin Gu, Yaoning Sun, Wangjun Cheng, Zhenzeng Chong, Xufeng Ma, Liufei Huang, Shilin Zhang, Yufeng Chen","doi":"10.1016/j.intermet.2024.108578","DOIUrl":"10.1016/j.intermet.2024.108578","url":null,"abstract":"<div><div>A novel AlCoCrFeNi<sub>2.1</sub> high-entropy alloy self-lubricating coating was prepared by multilayer graphene (MLG) enhancement. The AlCoCrFeNi<sub>2.1</sub>-MLG (3 wt%) high-entropy alloy self-lubricating coating was prepared on AISI1045 steel using laser cladding by introducing lubricant named MLG. The microstructure, phase structure, wear resistance and corrosion performance of the AlCoCrFeNi<sub>2.1</sub>-MLG coating were studied. It is shown that the microstructure of the AlCoCrFeNi<sub>2.1</sub>-MLG coating has typical dendritic (DR) and interdendritic (ID) structures, with the dendrites consisting of high density M<sub>23</sub>C<sub>6</sub> phase precipitation and FCC phase distributed in the interdendritic region. With the addition of MLG, the average hardness of the AlCoCrFeNi<sub>2.1</sub> coating increases from 306.71 HV to 486.68 HV (an increase of 58.68 %). The average coefficient of friction decreases from 0.59 to 0.48 (a reduction of 22.92 %). The wear rate decreases from 1.678 × 10<sup>- 6</sup> mm<sup>3</sup>·N<sup>− 1</sup> m<sup>−1</sup> to 0.825 × 10<sup>- 6</sup> mm<sup>3</sup>·N<sup>− 1</sup> m<sup>− 1</sup> (a reduction of 50.83 %). This is due to the formation of a lubricant film in the AlCoCrFeNi<sub>2.1</sub>-MLG coating. The wear mechanism changes from plastic deformation and abrasive debris wear to slight delamination and spalling of the lubricant film. However, the corrosion performance of the AlCoCrFeNi<sub>2.1</sub>-MLG coating is slightly reduced by the occurrence of micro-electro-coupling corrosion on the corroded surface. The M<sub>23</sub>C<sub>6</sub> phase is used as the anode and the FCC phase is used as the cathode. The subsequent generation of a passivation film prevents the appearance of severe electro-coupling corrosion. The wear resistance of the AlCoCrFeNi<sub>2.1</sub>-MLG coating is substantially improved while taking into account the corrosion performance. This study provides important values for laser cladding of self-lubricating composite coatings of high-entropy alloys.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"176 ","pages":"Article 108578"},"PeriodicalIF":4.3,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700271","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 : 2024-11-22DOI: 10.1016/j.intermet.2024.108577
Elisa Holzmann , Khemais Barienti , Mattia Guglielmi , Egbert Baake , Sebastian Herbst , Hans Jürgen Maier
The phase composition, microstructure and mechanical properties of arc-melted eutectic Nb-18.7Si (at.-%) alloys with different nano-ceramic particle addition (Al2O3, TiC, SiC, 5 mol.-%) were investigated. The results showed that ceramic Al2O3 and TiC nanoparticle are thermally and chemically stable and can be used to tailor phase composition and refine the microstructure, while SiC dissolves completely in the melt. Al2O3 and TiC nanoparticle were found mainly in two different areas: (1) at grain boundaries of eutectic structures and (2) on the phase boundaries of silicides inside the eutectics. The presence of the particles refined the microstructure down to nano-scale lamellae by functioning as heterogeneous nuclei for the silicide phase. Without nano particle addition, the Nb-18.7Si alloy was mainly composed of Nb solid solution (Nbss) and Nb3Si. The addition of 5 mol.-% Al2O3 promoted the decomposition of the Nb3Si phase and an ultrafine nano-scale lamellar eutectic structure (Nbss + α-Nb5Si3) formed. With the addition of 5 mol.-% TiC, primary Nb3Si and coarse Nbss were observed, as well as fine eutectic Nbss + γ-Nb5Si3 structures. The complete dissolution of SiC led to a hypereutectic alloy with primary Nb3Si and γ-Nb5Si3 phase, coarse Nbss and eutectic Nbss + γ-Nb5Si3 structures. The compressive strength was increased from 3068 MPa to 3446 MPa by adding 5 mol.-% Al2O3 due to the formation of the high strength α-Nb5Si3 phase, the ultrafine nano-scale lamellar structures of Nbss + α-Nb5Si3 and the strong interface of Nbss/α-Nb5Si3. However, the small grain size of the Nbss phase was not effective in inhibiting crack propagation. Crack bridging and branching seem to be important mechanisms at the Nbss phase to inhibit crack propagation. Therefore, the size and distribution of Nbss play a key role. The results indicate that a continuous Nbss phase with embedded silicide phase and coarse Nbss phases can inhibit crack propagation.
{"title":"Enhanced mechanical properties of Nb-18.7Si alloy by addition of ceramic nano particles for microstructural control","authors":"Elisa Holzmann , Khemais Barienti , Mattia Guglielmi , Egbert Baake , Sebastian Herbst , Hans Jürgen Maier","doi":"10.1016/j.intermet.2024.108577","DOIUrl":"10.1016/j.intermet.2024.108577","url":null,"abstract":"<div><div>The phase composition, microstructure and mechanical properties of arc-melted eutectic Nb-18.7Si (at.-%) alloys with different nano-ceramic particle addition (Al<sub>2</sub>O<sub>3</sub>, TiC, SiC, 5 mol.-%) were investigated. The results showed that ceramic Al<sub>2</sub>O<sub>3</sub> and TiC nanoparticle are thermally and chemically stable and can be used to tailor phase composition and refine the microstructure, while SiC dissolves completely in the melt. Al<sub>2</sub>O<sub>3</sub> and TiC nanoparticle were found mainly in two different areas: (1) at grain boundaries of eutectic structures and (2) on the phase boundaries of silicides inside the eutectics. The presence of the particles refined the microstructure down to nano-scale lamellae by functioning as heterogeneous nuclei for the silicide phase. Without nano particle addition, the Nb-18.7Si alloy was mainly composed of Nb solid solution (Nb<sub>ss</sub>) and Nb<sub>3</sub>Si. The addition of 5 mol.-% Al<sub>2</sub>O<sub>3</sub> promoted the decomposition of the Nb<sub>3</sub>Si phase and an ultrafine nano-scale lamellar eutectic structure (Nb<sub>ss</sub> + α-Nb<sub>5</sub>Si<sub>3</sub>) formed. With the addition of 5 mol.-% TiC, primary Nb<sub>3</sub>Si and coarse Nb<sub>ss</sub> were observed, as well as fine eutectic Nb<sub>ss</sub> + γ-Nb<sub>5</sub>Si<sub>3</sub> structures. The complete dissolution of SiC led to a hypereutectic alloy with primary Nb<sub>3</sub>Si and γ-Nb<sub>5</sub>Si<sub>3</sub> phase, coarse Nb<sub>ss</sub> and eutectic Nb<sub>ss</sub> + γ-Nb<sub>5</sub>Si<sub>3</sub> structures. The compressive strength was increased from 3068 MPa to 3446 MPa by adding 5 mol.-% Al<sub>2</sub>O<sub>3</sub> due to the formation of the high strength α-Nb<sub>5</sub>Si<sub>3</sub> phase, the ultrafine nano-scale lamellar structures of Nb<sub>ss</sub> + α-Nb<sub>5</sub>Si<sub>3</sub> and the strong interface of Nb<sub>ss</sub>/α-Nb<sub>5</sub>Si<sub>3</sub>. However, the small grain size of the Nb<sub>ss</sub> phase was not effective in inhibiting crack propagation. Crack bridging and branching seem to be important mechanisms at the Nb<sub>ss</sub> phase to inhibit crack propagation. Therefore, the size and distribution of Nb<sub>ss</sub> play a key role. The results indicate that a continuous Nb<sub>ss</sub> phase with embedded silicide phase and coarse Nb<sub>ss</sub> phases can inhibit crack propagation.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"176 ","pages":"Article 108577"},"PeriodicalIF":4.3,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700640","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 : 2024-11-21DOI: 10.1016/j.intermet.2024.108576
Gabriel L.B.G. Fontana , Payam Edalati , Shivam Dangwal , Kaveh Edalati , Renato B. Strozi , Ricardo Floriano
To make hydrogen a more viable energy carrier, various solutions for hydrogen storage have been developed, with significant recent progress in developing new high-entropy alloys (HEAs) that exhibit attractive hydrogen storage properties. In this paper, we investigated the crystal structure and hydrogen storage properties of a new medium-entropy alloy (MEA) ZrNbFeCo, designed using a combination of semi-empirical parameters and thermodynamic calculations via the CALPHAD method. The alloy was synthesized by arc melting under an argon atmosphere and subsequently characterized using comprehensive techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). These analyses revealed the presence of a major C14 Laves phase, with a compositional gradient and grain sizes ranging from microscale to nanoscale. The hydrogen storage properties were evaluated using pressure-composition isotherms (PCI) and kinetics curves. After a simple activation procedure, the alloy formed a C14 hydride and exhibited excellent properties to act as a vessel for hydrogen storage at room temperature. Under these conditions, the alloy was able to absorb up to 1.2 wt% of hydrogen (hydrogen-to-metal ratio of H/M ∼ 0.9), with fast absorption kinetics, reaching around 87 % of its maximum capacity after just 60s. The alloy also exhibited full reversibility and great stability through multiple absorption-desorption cycles, absorbing an average content of 1.1 wt% of hydrogen (H/M ∼ 0.82) after 8 cycles. The present results demonstrate that it is possible to practically employ semi-empirical and thermodynamics calculations, originally developed for HEAs, to develop new MEAs that exhibit appropriate microstructure and excellent hydrogen storage properties at room temperature.
{"title":"Crystal structure and hydrogen storage properties of ZrNbFeCo medium-entropy alloy","authors":"Gabriel L.B.G. Fontana , Payam Edalati , Shivam Dangwal , Kaveh Edalati , Renato B. Strozi , Ricardo Floriano","doi":"10.1016/j.intermet.2024.108576","DOIUrl":"10.1016/j.intermet.2024.108576","url":null,"abstract":"<div><div>To make hydrogen a more viable energy carrier, various solutions for hydrogen storage have been developed, with significant recent progress in developing new high-entropy alloys (HEAs) that exhibit attractive hydrogen storage properties. In this paper, we investigated the crystal structure and hydrogen storage properties of a new medium-entropy alloy (MEA) ZrNbFeCo, designed using a combination of semi-empirical parameters and thermodynamic calculations via the CALPHAD method. The alloy was synthesized by arc melting under an argon atmosphere and subsequently characterized using comprehensive techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). These analyses revealed the presence of a major C14 Laves phase, with a compositional gradient and grain sizes ranging from microscale to nanoscale. The hydrogen storage properties were evaluated using pressure-composition isotherms (PCI) and kinetics curves. After a simple activation procedure, the alloy formed a C14 hydride and exhibited excellent properties to act as a vessel for hydrogen storage at room temperature. Under these conditions, the alloy was able to absorb up to 1.2 wt% of hydrogen (hydrogen-to-metal ratio of H/M ∼ 0.9), with fast absorption kinetics, reaching around 87 % of its maximum capacity after just 60s. The alloy also exhibited full reversibility and great stability through multiple absorption-desorption cycles, absorbing an average content of 1.1 wt% of hydrogen (H/M ∼ 0.82) after 8 cycles. The present results demonstrate that it is possible to practically employ semi-empirical and thermodynamics calculations, originally developed for HEAs, to develop new MEAs that exhibit appropriate microstructure and excellent hydrogen storage properties at room temperature.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"176 ","pages":"Article 108576"},"PeriodicalIF":4.3,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700639","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 : 2024-11-16DOI: 10.1016/j.intermet.2024.108560
Liming Fu , Zhian Song , Qigui Yang , Te Zhu , Rui Ma , Mingpan Wan , Peng Zhang , Runsheng Yu , Xingzhong Cao
Understanding the strengthening mechanism of high entropy alloys (HEA) is vital to improve their mechanical properties. In this study, we thoroughly investigated the strengthening effect of L12 nanoprecipitates on the mechanical properties of the face-centered cubic (FCC) CoCrFeNi HEA. The L12 nanoprecipitates were introduced by adding titanium (Ti), niobium (Nb), and aluminum (Al). Following a series of heat treatments (aged at 400 °C, 600 °C, and 800 °C for 4 h), the samples aged at 800 °C exhibited a noticeable improvement in tensile strength compared to the CoCrFeNi-based alloy, while maintaining excellent ductility (elongation greater than 29 %). This enhanced in performance is primarily attributed to the synergistic effects of multiple strengthening mechanisms, with precipitation strengthening playing a particularly prominent role (. Transmission electron microscopy (TEM) results revealed that the volume fraction of L12 precipitates reached 35 %, with sizes around 12 nm. This study provides valuable theoretical insights for optimizing the composition and processing strategies of high entropy alloys and lays a solid foundation for the development of high-performance alloys suited to complex engineering applications.
{"title":"Microstructure evolution and tensile properties behavior during aging temperature of CoCrFeNi-based high entropy alloys","authors":"Liming Fu , Zhian Song , Qigui Yang , Te Zhu , Rui Ma , Mingpan Wan , Peng Zhang , Runsheng Yu , Xingzhong Cao","doi":"10.1016/j.intermet.2024.108560","DOIUrl":"10.1016/j.intermet.2024.108560","url":null,"abstract":"<div><div>Understanding the strengthening mechanism of high entropy alloys (HEA) is vital to improve their mechanical properties. In this study, we thoroughly investigated the strengthening effect of L1<sub>2</sub> nanoprecipitates on the mechanical properties of the face-centered cubic (FCC) CoCrFeNi HEA. The L1<sub>2</sub> nanoprecipitates were introduced by adding titanium (Ti), niobium (Nb), and aluminum (Al). Following a series of heat treatments (aged at 400 °C, 600 °C, and 800 °C for 4 h), the samples aged at 800 °C exhibited a noticeable improvement in tensile strength compared to the CoCrFeNi-based alloy, while maintaining excellent ductility (elongation greater than 29 %). This enhanced in performance is primarily attributed to the synergistic effects of multiple strengthening mechanisms, with precipitation strengthening playing a particularly prominent role (<span><math><mrow><mrow><mo>Δ</mo><msub><mi>σ</mi><mi>P</mi></msub><mo>=</mo><mn>385.6</mn><mi>M</mi><mi>P</mi><mi>a</mi></mrow><mo>)</mo></mrow></math></span>. Transmission electron microscopy (TEM) results revealed that the volume fraction of L1<sub>2</sub> precipitates reached 35 %, with sizes around 12 nm. This study provides valuable theoretical insights for optimizing the composition and processing strategies of high entropy alloys and lays a solid foundation for the development of high-performance alloys suited to complex engineering applications.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"176 ","pages":"Article 108560"},"PeriodicalIF":4.3,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659862","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}
This study explored the relationship between tribological performance and microstructural changes induced by heat treatment in a newly developed ZrNbTiVAl high-entropy alloy (HEA). The alloy was evaluated in its as-cast state and after heat treatments at 950 °C for 15, 20, and 25 h, with dry sliding experiments conducted against an alumina ball counterface. Advanced analytical techniques, including 3D optical profilometry, nanohardness testing, field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), and Micro-Raman spectroscopy, were employed for comprehensive surface analysis and to investigate oxide layer formation on the worn surfaces.
The study reveals a nuanced relationship between heat treatment duration, oxide layer formation, and frictional behavior in the ZrNbTiVAl high-entropy alloy (HEA). Increasing the heat treatment duration at 950 °C results in higher hardness (H) and a reduction in the modulus of elasticity (E) of the ZrNbTiVAl high-entropy alloy (HEA). Notably, wear rate and friction were lower in the as-cast and 15 h heat-treated conditions, despite their lower H/E and H³/E2 values compared to the 20 h and 25 h heat-treated states. Additionally, the wear mechanisms shift significantly, from mild adhesive/oxidative wear in the as-cast and 15 h conditions to severe adhesive/oxidative wear in the 20 h and 25 h conditions. This improved performance in the as-cast and 15 h conditions is attributed to the enrichment of Ti and V—elements recognized for their solid lubrication properties—and a reduced presence of Al-Zr intermetallics, which helps to minimize the formation of hard wear debris during dry sliding. These findings underscore the importance of optimizing heat treatment parameters to achieve superior tribological performance.
{"title":"Investigation of tribological properties of heat-treated ZrNbTiVAl high entropy alloy in dry sliding conditions","authors":"Neelima Khare , Poulami Chakraborty , Satish Chandra Mishra , Anurup Das , Praveen Kumar Limaye , Mahender Dev , Raghvendra Tewari","doi":"10.1016/j.intermet.2024.108573","DOIUrl":"10.1016/j.intermet.2024.108573","url":null,"abstract":"<div><div>This study explored the relationship between tribological performance and microstructural changes induced by heat treatment in a newly developed ZrNbTiVAl high-entropy alloy (HEA). The alloy was evaluated in its as-cast state and after heat treatments at 950 °C for 15, 20, and 25 h, with dry sliding experiments conducted against an alumina ball counterface. Advanced analytical techniques, including 3D optical profilometry, nanohardness testing, field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), and Micro-Raman spectroscopy, were employed for comprehensive surface analysis and to investigate oxide layer formation on the worn surfaces.</div><div>The study reveals a nuanced relationship between heat treatment duration, oxide layer formation, and frictional behavior in the ZrNbTiVAl high-entropy alloy (HEA). Increasing the heat treatment duration at 950 °C results in higher hardness (H) and a reduction in the modulus of elasticity (E) of the ZrNbTiVAl high-entropy alloy (HEA). Notably, wear rate and friction were lower in the as-cast and 15 h heat-treated conditions, despite their lower H/E and H³/E<sup>2</sup> values compared to the 20 h and 25 h heat-treated states. Additionally, the wear mechanisms shift significantly, from mild adhesive/oxidative wear in the as-cast and 15 h conditions to severe adhesive/oxidative wear in the 20 h and 25 h conditions. This improved performance in the as-cast and 15 h conditions is attributed to the enrichment of Ti and V—elements recognized for their solid lubrication properties—and a reduced presence of Al-Zr intermetallics, which helps to minimize the formation of hard wear debris during dry sliding. These findings underscore the importance of optimizing heat treatment parameters to achieve superior tribological performance.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"176 ","pages":"Article 108573"},"PeriodicalIF":4.3,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659829","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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