Pub Date : 2026-01-13DOI: 10.1016/j.msea.2026.149783
Huaijin Wang , Bohua Yu , Ning Ding , Hongmei Chen , Jiayin Chen , Chi Zhang , Xinxin Yang , Zeyun Cai , Guoqiang Xie
High-entropy and medium-entropy alloys (HEAs/MEAs) with face-centered cubic (FCC) structures have attracted significant interest. However, their low strength limits their use in structural applications. Traditional strengthening methods often sacrifice ductility to improve strength. This issue is particularly severe in Co-free alloys with high Cr content, which tend to form brittle precipitates during heat treatment. This study aims to mitigate the strength-ductility trade-off in a Co-free Ni2Cr2Fe MEA through a heterogeneous grain structure. After cold rolling and short-term high-temperature annealing (950 °C, 2 min), the alloy exhibits a yield strength of 1009 MPa and a fracture elongation of 21 %, without second phase strengthening or complex alloying. The microstructure includes non-recrystallized regions (NRX) with high dislocation density and recrystallized regions (RX) with ultrafine grains. Dislocation strengthening in the NRX regions contributes mainly to the yield strength. The sub-structures in the deformed regions sustain plastic deformation and promote uniform strain distribution. These findings provide insights into improving the strength-ductility balance in high-Cr content alloys.
{"title":"Mitigate the strength-ductility trade-off in high Cr content Ni2Cr2Fe MEA via heterogeneous structure design","authors":"Huaijin Wang , Bohua Yu , Ning Ding , Hongmei Chen , Jiayin Chen , Chi Zhang , Xinxin Yang , Zeyun Cai , Guoqiang Xie","doi":"10.1016/j.msea.2026.149783","DOIUrl":"10.1016/j.msea.2026.149783","url":null,"abstract":"<div><div>High-entropy and medium-entropy alloys (HEAs/MEAs) with face-centered cubic (FCC) structures have attracted significant interest. However, their low strength limits their use in structural applications. Traditional strengthening methods often sacrifice ductility to improve strength. This issue is particularly severe in Co-free alloys with high Cr content, which tend to form brittle precipitates during heat treatment. This study aims to mitigate the strength-ductility trade-off in a Co-free Ni<sub>2</sub>Cr<sub>2</sub>Fe MEA through a heterogeneous grain structure. After cold rolling and short-term high-temperature annealing (950 °C, 2 min), the alloy exhibits a yield strength of 1009 MPa and a fracture elongation of 21 %, without second phase strengthening or complex alloying. The microstructure includes non-recrystallized regions (NRX) with high dislocation density and recrystallized regions (RX) with ultrafine grains. Dislocation strengthening in the NRX regions contributes mainly to the yield strength. The sub-structures in the deformed regions sustain plastic deformation and promote uniform strain distribution. These findings provide insights into improving the strength-ductility balance in high-Cr content alloys.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149783"},"PeriodicalIF":7.0,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973661","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 : 2026-01-12DOI: 10.1016/j.msea.2026.149779
Tingxiao Yu , Honglong Zhao , Qingdong Qin , Kai Feng , Juan Li , Chuang Yang , Yu Zeng
Achieving a high-quality joint in refractory high-entropy alloys (RHEAs) remains a significant challenge. In the present study, an appropriate filler metal of TiZrCuNi was selected to successfully join TiVNbTa RHEA using vacuum brazing. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and shear tests were used to systematically study the interfacial microstructure and mechanical properties of the joints. The results showed that the brazing seam consists of a diffusion-affected zone (Zone I) and a central brazed zone (Zone II), with a convex structure formed between these two zones. TEM images revealed α-Ti(Zr) nano-precipitates in Zone I. As the brazing temperature increased, the thickness of Zone I gradually increased, while the volume fraction of the blocky α-Ti phase in Zone II significantly decreased. The shear strength of the joints initially increased and then decreased with rising brazing temperature, reaching an optimal value of 179 ± 8 MPa after brazing at 880 °C for 15 min. The enhanced bonding strength of the joint is attributed to the interlocking effect of the convex structure and nano-precipitation strengthening. This study provides valuable insights into the welding challenges of TiVNbTa RHEA, offering guidance for achieving high-quality welding of RHEAs.
{"title":"Enhancing the interfacial strength of TiVNbTa refractory high entropy alloy joint for vacuum brazed via convex structure with nano-precipitates","authors":"Tingxiao Yu , Honglong Zhao , Qingdong Qin , Kai Feng , Juan Li , Chuang Yang , Yu Zeng","doi":"10.1016/j.msea.2026.149779","DOIUrl":"10.1016/j.msea.2026.149779","url":null,"abstract":"<div><div>Achieving a high-quality joint in refractory high-entropy alloys (RHEAs) remains a significant challenge. In the present study, an appropriate filler metal of TiZrCuNi was selected to successfully join TiVNbTa RHEA using vacuum brazing. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and shear tests were used to systematically study the interfacial microstructure and mechanical properties of the joints. The results showed that the brazing seam consists of a diffusion-affected zone (Zone I) and a central brazed zone (Zone II), with a convex structure formed between these two zones. TEM images revealed α-Ti(Zr) nano-precipitates in Zone I. As the brazing temperature increased, the thickness of Zone I gradually increased, while the volume fraction of the blocky α-Ti phase in Zone II significantly decreased. The shear strength of the joints initially increased and then decreased with rising brazing temperature, reaching an optimal value of 179 ± 8 MPa after brazing at 880 °C for 15 min. The enhanced bonding strength of the joint is attributed to the interlocking effect of the convex structure and nano-precipitation strengthening. This study provides valuable insights into the welding challenges of TiVNbTa RHEA, offering guidance for achieving high-quality welding of RHEAs.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149779"},"PeriodicalIF":7.0,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973532","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 presents an investigation into the tensile creep behavior of the Ti-43Al-9V-0.2Y alloy characterized by α2/γ and β0/γ lamellar microstructures, following heat treatment at various temperatures and under differing levels of applied stress. The study explores the intricate relationships among microstructural evolution, phase orientation rotation, interface energy, and failure mechanisms. The creep behavior of the alloy exhibits a pronounced temperature dependence, indicating the presence of distinct creep mechanisms at varying temperatures. During the creep process, the microstructural transformation is characterized by the decomposition of the lamellae and the α2→γ phase transition. The rotation of the orientation relationship of β0/γ lamellae from to leads to a significant increase in the interface energy of the new orientation relationship, which becomes a preferential site for defect generation. At 800 °C high temperature, although the dynamic recrystallization in the matrix of the β0 phase alleviates stress concentration, the primary slip system of the γ phase is simultaneously altered to (111)//[101], resulting in the formation of the K-W pinning structure. Consequently, the plasticity of the sample deteriorates further.
{"title":"The effects of various temperatures and stress levels on the microstructure and failure mechanism of Ti-43Al-9V-0.2Y alloy after creep","authors":"Yang-jie Gao, Hai-tao Jiang, Shi-wei Tian, Si-yuan Zhang, Chun-hui Wang, Yi Wu, Hui Zhang","doi":"10.1016/j.msea.2026.149771","DOIUrl":"10.1016/j.msea.2026.149771","url":null,"abstract":"<div><div>This study presents an investigation into the tensile creep behavior of the Ti-43Al-9V-0.2Y alloy characterized by α<sub>2</sub>/γ and β<sub>0</sub>/γ lamellar microstructures, following heat treatment at various temperatures and under differing levels of applied stress. The study explores the intricate relationships among microstructural evolution, phase orientation rotation, interface energy, and failure mechanisms. The creep behavior of the alloy exhibits a pronounced temperature dependence, indicating the presence of distinct creep mechanisms at varying temperatures. During the creep process, the microstructural transformation is characterized by the decomposition of the lamellae and the α<sub>2</sub>→γ phase transition. The rotation of the orientation relationship of β<sub>0</sub>/γ lamellae from <span><math><mrow><mo><</mo><mn>110</mn><msub><mo>></mo><mi>γ</mi></msub><mo>/</mo><mo>/</mo><mo><</mo><mn>111</mn><msub><mo>></mo><msub><mi>β</mi><mn>0</mn></msub></msub></mrow></math></span> to <span><math><mrow><mo><</mo><mn>110</mn><msub><mo>></mo><mi>γ</mi></msub><mo>/</mo><mo>/</mo><mo><</mo><mn>100</mn><msub><mo>></mo><msub><mi>β</mi><mn>0</mn></msub></msub></mrow></math></span> leads to a significant increase in the interface energy of the new orientation relationship, which becomes a preferential site for defect generation. At 800 °C high temperature, although the dynamic recrystallization in the matrix of the β<sub>0</sub> phase alleviates stress concentration, the primary slip system of the γ phase is simultaneously altered to (111)//[101], resulting in the formation of the K-W pinning structure. Consequently, the plasticity of the sample deteriorates further.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149771"},"PeriodicalIF":7.0,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973663","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 : 2026-01-12DOI: 10.1016/j.msea.2026.149777
Fuming Yang , Si-Wei Liu , Ahmed Y. Elghazouli
Wire-based laser directed energy deposition, referred to as DED-LB or WLAM, is an emerging additive method using laser-melted wire feedstock, offering high deposition rate, smooth surfaces, and high precision. These capabilities indicate strong potential for construction, particularly for complex and optimised components, yet structural adoption necessitates in-depth assessments of mechanical and microstructural properties. This study describes a detailed experimental investigation into the mechanical behaviour and microstructural characteristics of ER70S-6 normal-strength and ER110S-G high-strength steels produced by DED-LB, with focus on property variability and orientation-induced anisotropy, compared with wire-based arc directed energy deposition (i.e., DED-Arc or WAAM). Tensile tests are performed on as-built specimens extracted from various orientations, with 3D scanning quantifying surface undulations, and digital image correlation recording full-field strains. The microstructures are characterised using optical and scanning electron microscopy and electron backscatter diffraction, and microhardness is mapped to microstructural phases. The results show that both steels show favourable stiffness properties and ductility with modest orientation-dependent anisotropy, where ultimate strength ratios across orientations are 0.95–1.00, and elongation ratios are 0.94–1.06. Most coefficients of variation for tensile strength and fracture elongation are found to be below 0.07, comparable to conventional steels. Dominant microstructural phases are shown to be uniformly distributed, with observed layer boundary regions in agreement with local microhardness. Relative to DED-Arc, DED-LB steels, especially for the high-strength grade, are shown to exhibit higher ductility with reduced orientation sensitivity while maintaining comparable strengths. Overall, the findings provide as-built dataset for informing wire-based process assessment and selection for civil engineering applications.
{"title":"Tensile behaviour and microstructure of wire-based laser directed energy deposited normal- and high-strength steels","authors":"Fuming Yang , Si-Wei Liu , Ahmed Y. Elghazouli","doi":"10.1016/j.msea.2026.149777","DOIUrl":"10.1016/j.msea.2026.149777","url":null,"abstract":"<div><div>Wire-based laser directed energy deposition, referred to as DED-LB or WLAM, is an emerging additive method using laser-melted wire feedstock, offering high deposition rate, smooth surfaces, and high precision. These capabilities indicate strong potential for construction, particularly for complex and optimised components, yet structural adoption necessitates in-depth assessments of mechanical and microstructural properties. This study describes a detailed experimental investigation into the mechanical behaviour and microstructural characteristics of ER70S-6 normal-strength and ER110S-G high-strength steels produced by DED-LB, with focus on property variability and orientation-induced anisotropy, compared with wire-based arc directed energy deposition (i.e., DED-Arc or WAAM). Tensile tests are performed on as-built specimens extracted from various orientations, with 3D scanning quantifying surface undulations, and digital image correlation recording full-field strains. The microstructures are characterised using optical and scanning electron microscopy and electron backscatter diffraction, and microhardness is mapped to microstructural phases. The results show that both steels show favourable stiffness properties and ductility with modest orientation-dependent anisotropy, where ultimate strength ratios across orientations are 0.95–1.00, and elongation ratios are 0.94–1.06. Most coefficients of variation for tensile strength and fracture elongation are found to be below 0.07, comparable to conventional steels. Dominant microstructural phases are shown to be uniformly distributed, with observed layer boundary regions in agreement with local microhardness. Relative to DED-Arc, DED-LB steels, especially for the high-strength grade, are shown to exhibit higher ductility with reduced orientation sensitivity while maintaining comparable strengths. Overall, the findings provide as-built dataset for informing wire-based process assessment and selection for civil engineering applications.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149777"},"PeriodicalIF":7.0,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973534","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 : 2026-01-11DOI: 10.1016/j.msea.2026.149769
Peng Lyu , Lei Hao , Ken Deng , Shun Guo , Yu Liu , Xinlin Liu , Haixia Liu
In the present study, CoCrFeNiZrx (x = 0.1, 0.3, 0.5, 1) high-entropy alloys (HEAs) were successfully fabricated using vacuum arc melting. The effects of Zr content on the microstructure, mechanical properties, wear resistance, and corrosion behavior were systematically examined. With increasing Zr content, the phase structure of the alloys progressively evolved from a face-centered cubic (FCC) + Laves phase assemblage to a Laves + body-centered cubic (BCC) phase assemblage. This evolution was accompanied by a corresponding microstructural transformation from a dendritic structure to eutectic and hypereutectic morphologies. Mechanical property characterization revealed that the addition of Zr significantly improved the hardness and strength of the alloys through the combined effects of solid-solution strengthening, second-phase strengthening, and interfacial strengthening. Among these alloys, the CoCrFeNiZr0.3 alloy exhibited an optimal strength-plasticity balance. It showed yield and tensile strengths of 418 and 609 MPa, respectively, while retaining an elongation at break of 20.87 %. The CoCrFeNiZr1 alloy achieved the highest hardness of 897.54 HV. However, its ductility decreased drastically. As Zr content increased, the wear mechanism transitioned from abrasive wear to oxidative wear, resulting in a marked improvement in wear resistance. Electrochemical measurements revealed that Zr addition was negatively correlated with the corrosion resistance of the alloys. Nevertheless, all compositions except CoCrFeNiZr1 exhibited corrosion resistance superior to that of SS304 stainless steel. The present study clarified the mechanism by which Zr content modulated the microstructure of HEAs. As a result, a balance between optimized mechanical properties and corrosion resistance was achieved in these alloys.
{"title":"Correlation between microstructural regulation and material properties: Effects of Zr content on mechanical and corrosion behaviors of CoCrFeNi high-entropy alloy","authors":"Peng Lyu , Lei Hao , Ken Deng , Shun Guo , Yu Liu , Xinlin Liu , Haixia Liu","doi":"10.1016/j.msea.2026.149769","DOIUrl":"10.1016/j.msea.2026.149769","url":null,"abstract":"<div><div>In the present study, CoCrFeNiZr<sub><em>x</em></sub> (<em>x</em> = 0.1, 0.3, 0.5, 1) high-entropy alloys (HEAs) were successfully fabricated using vacuum arc melting. The effects of Zr content on the microstructure, mechanical properties, wear resistance, and corrosion behavior were systematically examined. With increasing Zr content, the phase structure of the alloys progressively evolved from a face-centered cubic (FCC) + Laves phase assemblage to a Laves + body-centered cubic (BCC) phase assemblage. This evolution was accompanied by a corresponding microstructural transformation from a dendritic structure to eutectic and hypereutectic morphologies. Mechanical property characterization revealed that the addition of Zr significantly improved the hardness and strength of the alloys through the combined effects of solid-solution strengthening, second-phase strengthening, and interfacial strengthening. Among these alloys, the CoCrFeNiZr<sub>0.3</sub> alloy exhibited an optimal strength-plasticity balance. It showed yield and tensile strengths of 418 and 609 MPa, respectively, while retaining an elongation at break of 20.87 %. The CoCrFeNiZr<sub>1</sub> alloy achieved the highest hardness of 897.54 HV. However, its ductility decreased drastically. As Zr content increased, the wear mechanism transitioned from abrasive wear to oxidative wear, resulting in a marked improvement in wear resistance. Electrochemical measurements revealed that Zr addition was negatively correlated with the corrosion resistance of the alloys. Nevertheless, all compositions except CoCrFeNiZr<sub>1</sub> exhibited corrosion resistance superior to that of SS304 stainless steel. The present study clarified the mechanism by which Zr content modulated the microstructure of HEAs. As a result, a balance between optimized mechanical properties and corrosion resistance was achieved in these alloys.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149769"},"PeriodicalIF":7.0,"publicationDate":"2026-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973519","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 : 2026-01-11DOI: 10.1016/j.msea.2026.149774
Faisal Mustafa, Ahmed Hanafy Ibrahim, Basil M. Darras
Repairing cracks in high-strength aluminum alloys, such as AA6061-T6, is challenging due to the poor repair quality and mechanical property degradation (i.e., strength reduction) often experienced with conventional repair techniques (i.e., fusion-based). This study investigates the use of the solid-state friction stir processing (FSP) for crack repairing in 6061-T6 aluminum alloy, followed by two post-FSP heat treatments aimed at enhancing repair quality and restoring material strength. Mechanical properties, microstructure evolution, and crystallographic analyses demonstrated that FSP alone improved strength to 199.2 MPa (62.8 % recovery) and ductility to 24.8 %, though properties remained below the as-received condition due to dissolution of strengthening precipitates. Post-FSP artificial aging (FSP + Aged) increased strength to 221.1 MPa but reduced ductility to 14.3 %. The most effective route, FSP + Solutionized + Aged, achieved 293.7 MPa (92.7 % recovery) with a uniform precipitate distribution and near-complete hardness recovery, though ductility dropped to 9 %. Microstructural observations revealed fine equiaxed grains in the stir zone, while fracture analysis showed a transition from ductile to mixed brittle-ductile behavior, confirming a strength-ductility trade-off. These findings demonstrate that combining FSP with solutionizing and aging can restore near-original strength, but challenges remain in balancing ductility. The study highlights the importance of tailoring post-FSP heat treatments for effective structural repair of precipitation-hardened alloys.
{"title":"Overcoming property degradation in 6061-T6 aluminum alloy: Crack repair by friction stir processing and tailored heat treatments","authors":"Faisal Mustafa, Ahmed Hanafy Ibrahim, Basil M. Darras","doi":"10.1016/j.msea.2026.149774","DOIUrl":"10.1016/j.msea.2026.149774","url":null,"abstract":"<div><div>Repairing cracks in high-strength aluminum alloys, such as AA6061-T6, is challenging due to the poor repair quality and mechanical property degradation (i.e., strength reduction) often experienced with conventional repair techniques (i.e., fusion-based). This study investigates the use of the solid-state friction stir processing (FSP) for crack repairing in 6061-T6 aluminum alloy, followed by two post-FSP heat treatments aimed at enhancing repair quality and restoring material strength. Mechanical properties, microstructure evolution, and crystallographic analyses demonstrated that FSP alone improved strength to 199.2 MPa (62.8 % recovery) and ductility to 24.8 %, though properties remained below the as-received condition due to dissolution of strengthening precipitates. Post-FSP artificial aging (FSP + Aged) increased strength to 221.1 MPa but reduced ductility to 14.3 %. The most effective route, FSP + Solutionized + Aged, achieved 293.7 MPa (92.7 % recovery) with a uniform precipitate distribution and near-complete hardness recovery, though ductility dropped to 9 %. Microstructural observations revealed fine equiaxed grains in the stir zone, while fracture analysis showed a transition from ductile to mixed brittle-ductile behavior, confirming a strength-ductility trade-off. These findings demonstrate that combining FSP with solutionizing and aging can restore near-original strength, but challenges remain in balancing ductility. The study highlights the importance of tailoring post-FSP heat treatments for effective structural repair of precipitation-hardened alloys.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149774"},"PeriodicalIF":7.0,"publicationDate":"2026-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973586","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 : 2026-01-10DOI: 10.1016/j.msea.2026.149770
Donghui Wen , BeiBei Jiang , Tianlong Zhang , Mengqi Gao , Zhaowen Huang , Fengyu Kong , Yuanmin Zhu , Anding Wang , Qing Wang , Chain-Tsuan Liu
BCC-based high/medium-entropy alloys (H/MEAs) possess prominent high-temperature strength, low thermal expansion, and high thermal conductivity, making them a promising candidate for elevated-temperature applications. However, their limited deformability at room temperature (RT) hinders industrial implementation. Here, we report a novel cost-effective (FeCrNi)85(AlTi)15 MEA featuring a multiple-phase microstructure with BCC/L21, L21/BCC, and FCC/L12 coherent interfaces in the as-cast state. The strategic incorporation of L12-strengthened FCC matrix phase within brittle BCC and L21 matrices can activate hetero-deformation-induced (HDI) hardening effect, achieving an attractive compressive plasticity of 35 % at room temperature. The well-controlled L21-Ni2AlTi, BCC, and L12-Ni3(Al, Ti) nanoparticles coherently precipitate in BCC, L21, and FCC matrix phases, respectively, resulting in a super-high yield strength of 1850 MPa, outperforming existing B2/L21-strengthened BCC H/MEAs. The triple-coherent interface system demonstrates exceptional thermal stability, maintaining yield strengths of 850 MPa at 700 °C and 395 MPa at 800 °C. Moreover, this alloy exhibits a dynamic phase transformation-induced hardening effect during long-term aging due to the precipitation of σ-FeCr phase. These results provide a new strategy for overcoming the drawback of inadequate deformability in BCC-based alloys and developing novel advanced as-cast materials for high-temperature applications under compressive loading.
{"title":"Strong and deformable high-Al/Ti medium entropy alloy with good thermal stability via multiple coherent-precipitation","authors":"Donghui Wen , BeiBei Jiang , Tianlong Zhang , Mengqi Gao , Zhaowen Huang , Fengyu Kong , Yuanmin Zhu , Anding Wang , Qing Wang , Chain-Tsuan Liu","doi":"10.1016/j.msea.2026.149770","DOIUrl":"10.1016/j.msea.2026.149770","url":null,"abstract":"<div><div>BCC-based high/medium-entropy alloys (H/MEAs) possess prominent high-temperature strength, low thermal expansion, and high thermal conductivity, making them a promising candidate for elevated-temperature applications. However, their limited deformability at room temperature (RT) hinders industrial implementation. Here, we report a novel cost-effective (FeCrNi)<sub>85</sub>(AlTi)<sub>15</sub> MEA featuring a multiple-phase microstructure with BCC/L2<sub>1</sub>, L2<sub>1</sub>/BCC, and FCC/L1<sub>2</sub> coherent interfaces in the as-cast state. The strategic incorporation of L1<sub>2</sub>-strengthened FCC matrix phase within brittle BCC and L2<sub>1</sub> matrices can activate hetero-deformation-induced (HDI) hardening effect, achieving an attractive compressive plasticity of 35 % at room temperature. The well-controlled L2<sub>1</sub>-Ni<sub>2</sub>AlTi, BCC, and L1<sub>2</sub>-Ni<sub>3</sub>(Al, Ti) nanoparticles coherently precipitate in BCC, L2<sub>1,</sub> and FCC matrix phases, respectively, resulting in a super-high yield strength of 1850 MPa, outperforming existing B2/L2<sub>1</sub>-strengthened BCC H/MEAs. The triple-coherent interface system demonstrates exceptional thermal stability, maintaining yield strengths of 850 MPa at 700 °C and 395 MPa at 800 °C. Moreover, this alloy exhibits a dynamic phase transformation-induced hardening effect during long-term aging due to the precipitation of σ-FeCr phase. These results provide a new strategy for overcoming the drawback of inadequate deformability in BCC-based alloys and developing novel advanced as-cast materials for high-temperature applications under compressive loading.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149770"},"PeriodicalIF":7.0,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973521","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 : 2026-01-10DOI: 10.1016/j.msea.2025.149685
Xiangyu Wang , Chao He , Yajun Dai , Yongjie Liu , Chong Wang , Qingyuan Wang
This work investigates the mechanisms governing micropore nucleation and fatigue crack propagation in a directionally solidified (DS) Ni-based superalloy (IC10) subjected to very high cycle fatigue (VHCF) at 850 °C. By employing advanced characterization techniques, including scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and electron channeling contrast imaging (ECCI), we show that fatigue cracks predominantly initiate from internal casting pores and propagate in an {111} planar-slip-driven mode. Two distinct modes of early crack growth were identified: (1) a tortuous pathway mediated by interconnected circular and short rod-like micro-voids, and (2) discontinuous propagation along the trace direction of a specific slip-plane. Our observations further demonstrate that such crack-growth behavior is strongly influenced by localized microstructural evolution, including cyclic slip-band deformation, the formation of low-angle grain boundaries, and their interactions with the γ/γ′ interface. These coupled processes promote micro-void nucleation and accelerate subsequent crack extension. Overall, the results provide new insights into the VHCF failure of DS Ni-based superalloys and offer guidance for microstructural optimization and life prediction in high-performance DS alloys.
{"title":"VHCF behavior and micro-void formation in a directionally solidified nickel-based superalloy","authors":"Xiangyu Wang , Chao He , Yajun Dai , Yongjie Liu , Chong Wang , Qingyuan Wang","doi":"10.1016/j.msea.2025.149685","DOIUrl":"10.1016/j.msea.2025.149685","url":null,"abstract":"<div><div>This work investigates the mechanisms governing micropore nucleation and fatigue crack propagation in a directionally solidified (DS) Ni-based superalloy (IC10) subjected to very high cycle fatigue (VHCF) at 850 °C. By employing advanced characterization techniques, including scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and electron channeling contrast imaging (ECCI), we show that fatigue cracks predominantly initiate from internal casting pores and propagate in an {111} planar-slip-driven mode. Two distinct modes of early crack growth were identified: (1) a tortuous pathway mediated by interconnected circular and short rod-like micro-voids, and (2) discontinuous propagation along the trace direction of a specific slip-plane. Our observations further demonstrate that such crack-growth behavior is strongly influenced by localized microstructural evolution, including cyclic slip-band deformation, the formation of low-angle grain boundaries, and their interactions with the γ/γ′ interface. These coupled processes promote micro-void nucleation and accelerate subsequent crack extension. Overall, the results provide new insights into the VHCF failure of DS Ni-based superalloys and offer guidance for microstructural optimization and life prediction in high-performance DS alloys.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149685"},"PeriodicalIF":7.0,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973537","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 : 2026-01-10DOI: 10.1016/j.msea.2026.149763
Wenke Wang , Yu Chen , Zhifei Zhao , Zheyue Ai , Wenhui Guo , Yang Guo , Jianxun Zhang
The micro-region tensile properties of a 12 %Cr/NiCrMoV dissimilar metal welded joint (DMWJ) with a buttering layer were investigated. The yield strength (YS), ultimate tensile strength (UTS), strain hardening exponent, and strain hardening rate were obtained from 54 adjacent tensile specimens. The results showed that the micro-region strength and strain hardening exponent were not uniformly distributed across the DMWJ. The YS values of the 12 %Cr base metal (BM1), buttering layer (BL), weld metal (WM), and 30Cr2Ni4MoV base metal (BM2) were 751 MPa, 613 MPa, 705 MPa, and 793 MPa, respectively. The corresponding UTS values were 860 MPa, 718 MPa, 822 MPa, and 909 MPa. The strain hardening exponents (n2) were 0.079, 0.071, 0.086, and 0.083, respectively. The inferior strength and hardening ability of the BL originated from its blocky ferrite, coarse carbides, low KAM value (0.77°), and relatively coarse grains (3.05 μm). In the heat-affected zones (HAZ1 and HAZ2), strength decreased while the strain hardening exponent increased from the coarse-grain zone (CGZ) toward the fine-grain zone (FGZ), consistent with the gradual refinement of lath martensite. The true stress-strain curves revealed two stages of strain hardening, represented by exponents n1 and n2. The n2 value, which characterizes the middle and late stages of plastic deformation, was more sensitive to microstructural variation. The strength calculated using n2 and microhardness showed good agreement with the measured layered-tensile strength, indicating that the layered tensile method effectively avoids size effects and provides reliable micro-region strength. Micro-region mechanical properties without size-effect could be obtained by layered tensile test, which provides accurate assessment for crack calculation and structural integrity of DMWJs.
{"title":"Micro-region strength and strain hardening behavior of 12 %Cr/NiCrMoV dissimilar metal welded joint of steam turbine rotor","authors":"Wenke Wang , Yu Chen , Zhifei Zhao , Zheyue Ai , Wenhui Guo , Yang Guo , Jianxun Zhang","doi":"10.1016/j.msea.2026.149763","DOIUrl":"10.1016/j.msea.2026.149763","url":null,"abstract":"<div><div>The micro-region tensile properties of a 12 %Cr/NiCrMoV dissimilar metal welded joint (DMWJ) with a buttering layer were investigated. The yield strength (YS), ultimate tensile strength (UTS), strain hardening exponent, and strain hardening rate were obtained from 54 adjacent tensile specimens. The results showed that the micro-region strength and strain hardening exponent were not uniformly distributed across the DMWJ. The YS values of the 12 %Cr base metal (BM1), buttering layer (BL), weld metal (WM), and 30Cr2Ni4MoV base metal (BM2) were 751 MPa, 613 MPa, 705 MPa, and 793 MPa, respectively. The corresponding UTS values were 860 MPa, 718 MPa, 822 MPa, and 909 MPa. The strain hardening exponents (n<sub>2</sub>) were 0.079, 0.071, 0.086, and 0.083, respectively. The inferior strength and hardening ability of the BL originated from its blocky ferrite, coarse carbides, low KAM value (0.77°), and relatively coarse grains (3.05 μm). In the heat-affected zones (HAZ1 and HAZ2), strength decreased while the strain hardening exponent increased from the coarse-grain zone (CGZ) toward the fine-grain zone (FGZ), consistent with the gradual refinement of lath martensite. The true stress-strain curves revealed two stages of strain hardening, represented by exponents n<sub>1</sub> and n<sub>2</sub>. The n<sub>2</sub> value, which characterizes the middle and late stages of plastic deformation, was more sensitive to microstructural variation. The strength calculated using n<sub>2</sub> and microhardness showed good agreement with the measured layered-tensile strength, indicating that the layered tensile method effectively avoids size effects and provides reliable micro-region strength. Micro-region mechanical properties without size-effect could be obtained by layered tensile test, which provides accurate assessment for crack calculation and structural integrity of DMWJs.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149763"},"PeriodicalIF":7.0,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922913","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 : 2026-01-09DOI: 10.1016/j.msea.2026.149765
Guangjing Liao , Pan Xie , Libo Fu , Hu Li , Guojing Chen , Hailong Cong , Cuilan Wu
Allvac 718Plus (hereafter termed 718Plus) is a polycrystalline nickel-based superalloy developed from the widely used Inconel 718, with the key compositional change being the introduction of cobalt. Despite its commercial use, the site occupancy of Co atoms in δ, η, γ′, and γ″ phases, as well as the influence mechanism of cobalt on the precipitate evolution and mechanical properties of 718Plus, remains insufficiently elucidated. In this study, we systematically investigate the partitioning and role of cobalt in governing grain boundary and intragranular precipitation in polycrystalline 718Plus. The results demonstrate that the majority of the cobalt exhibits a partitioning preference for the γ matrix. In the δ, η, γ′, and γ″ phases, atomic-resolution EDS analyses and first-principles calculations confirm that cobalt preferentially occupies nickel sublattice sites. Increasing cobalt content lowers the solubility of Ni, Nb, and Ti element in the γ matrix and promotes their partitioning into the δ, η, and γ′ precipitates. This redistribution promotes the formation of the η/δ phase during solution treatment. An increase in the η/δ phase fraction not only reduces the volume fraction of the γ″ phase but also that of the γ′ phase when the increase becomes excessive during subsequent aging treatment. Consequently, the diminished γ″ phase fraction enhances plasticity but lowers the tensile and yield strength. Additionally, an excessively high η/δ phase fraction compromises ductility. These findings provide fundamental insight into the cobalt-mediated precipitation mechanisms in nickel-based polycrystalline superalloys and offer valuable guidance for the design of next-generation high-performance alloy compositions.
{"title":"Influence of cobalt content on the precipitates and mechanical properties in nickel-based polycrystalline superalloys","authors":"Guangjing Liao , Pan Xie , Libo Fu , Hu Li , Guojing Chen , Hailong Cong , Cuilan Wu","doi":"10.1016/j.msea.2026.149765","DOIUrl":"10.1016/j.msea.2026.149765","url":null,"abstract":"<div><div>Allvac 718Plus (hereafter termed 718Plus) is a polycrystalline nickel-based superalloy developed from the widely used Inconel 718, with the key compositional change being the introduction of cobalt. Despite its commercial use, the site occupancy of Co atoms in δ, η, γ′, and γ″ phases, as well as the influence mechanism of cobalt on the precipitate evolution and mechanical properties of 718Plus, remains insufficiently elucidated. In this study, we systematically investigate the partitioning and role of cobalt in governing grain boundary and intragranular precipitation in polycrystalline 718Plus. The results demonstrate that the majority of the cobalt exhibits a partitioning preference for the γ matrix. In the δ, η, γ′, and γ″ phases, atomic-resolution EDS analyses and first-principles calculations confirm that cobalt preferentially occupies nickel sublattice sites. Increasing cobalt content lowers the solubility of Ni, Nb, and Ti element in the γ matrix and promotes their partitioning into the δ, η, and γ′ precipitates. This redistribution promotes the formation of the η/δ phase during solution treatment. An increase in the η/δ phase fraction not only reduces the volume fraction of the γ″ phase but also that of the γ′ phase when the increase becomes excessive during subsequent aging treatment. Consequently, the diminished γ″ phase fraction enhances plasticity but lowers the tensile and yield strength. Additionally, an excessively high η/δ phase fraction compromises ductility. These findings provide fundamental insight into the cobalt-mediated precipitation mechanisms in nickel-based polycrystalline superalloys and offer valuable guidance for the design of next-generation high-performance alloy compositions.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149765"},"PeriodicalIF":7.0,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973520","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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