Pub Date : 2026-01-31DOI: 10.1016/j.intermet.2026.109191
Lushan Li , Le Chang , Yuan Gu , Jianping Zhao , Jinling Zhao , Tao Dai
This study employs a hybrid Monte Carlo/Molecular Dynamics (MC/MD) method to systematically investigate the effects of varying atomic ratios (Ni/Co/Cr contents ranging from 20 to 60 at.%) on the formation of Short-Range Order (SRO) and the mechanical properties of the NiCoCr ternary system. The degree of SRO was quantified by calculating Warren-Cowley parameters, and the deformation behaviors of structures with SRO were compared against Random Solid Solution models under uniaxial tension. The results indicate that SRO structures significantly enhance the alloy's unstable stacking fault energy and yield strength. Microstructural analysis reveals that Ni-Ni clusters play a dual role in SRO structures: dislocations preferentially nucleate along the edges of Ni-Ni clusters, while these clusters simultaneously exert a pinning effect, hindering dislocation slip and propagation. Furthermore, the investigation into atomic ratio variations reveals that as Ni content increases, the system tends to form a continuous network of Ni-Ni clusters. Based on the simulation results, this study establishes a theoretical prediction model incorporating lattice friction, elastic misfit strengthening, and chemical bond-breaking strengthening. This model successfully captures the variation laws of yield strength with respect to atomic ratio and SRO degree. This work not only reveals the physical origins of SRO strengthening but also provides a theoretical basis for the compositional design of high-performance medium-entropy alloys.
{"title":"Compositional control of chemical short-range order and yield strength in NiCoCr medium-entropy alloys","authors":"Lushan Li , Le Chang , Yuan Gu , Jianping Zhao , Jinling Zhao , Tao Dai","doi":"10.1016/j.intermet.2026.109191","DOIUrl":"10.1016/j.intermet.2026.109191","url":null,"abstract":"<div><div>This study employs a hybrid Monte Carlo/Molecular Dynamics (MC/MD) method to systematically investigate the effects of varying atomic ratios (Ni/Co/Cr contents ranging from 20 to 60 at.%) on the formation of Short-Range Order (SRO) and the mechanical properties of the NiCoCr ternary system. The degree of SRO was quantified by calculating Warren-Cowley parameters, and the deformation behaviors of structures with SRO were compared against Random Solid Solution models under uniaxial tension. The results indicate that SRO structures significantly enhance the alloy's unstable stacking fault energy and yield strength. Microstructural analysis reveals that Ni-Ni clusters play a dual role in SRO structures: dislocations preferentially nucleate along the edges of Ni-Ni clusters, while these clusters simultaneously exert a pinning effect, hindering dislocation slip and propagation. Furthermore, the investigation into atomic ratio variations reveals that as Ni content increases, the system tends to form a continuous network of Ni-Ni clusters. Based on the simulation results, this study establishes a theoretical prediction model incorporating lattice friction, elastic misfit strengthening, and chemical bond-breaking strengthening. This model successfully captures the variation laws of yield strength with respect to atomic ratio and SRO degree. This work not only reveals the physical origins of SRO strengthening but also provides a theoretical basis for the compositional design of high-performance medium-entropy alloys.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"191 ","pages":"Article 109191"},"PeriodicalIF":4.8,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075910","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 : 2026-01-29DOI: 10.1016/j.intermet.2026.109180
Jiajun Yuan , Zengmin Shi , Lei Dai , Xicong Ye , Long Xu , Junwen Gao , Panxing Liu
Conventional alloy design often targets a single universally optimal composition. This paradigm is challenged by a ‘threat-matched’ synergistic alloying strategy in (CoCrFeNi)85TaxMo15-x eutectic high-entropy alloys (EHEAs), prepared by vacuum arc melting, enabling remarkable environment-specific performance. Systematic tuning of the Ta/Mo ratio yields a eutectic (CoCrFeNi)85Ta5Mo10 alloy with exceptional properties of ∼1.7 GPa yield strength and 31.7 % fracture strain. Notably, corrosion resistance shifts with environment. In 0.6 M NaCl, a high-Ta alloy (TM10-5) offers a superior protection via a robust Ta2O5 barrier; in aggressive 0.6 M NH4Cl, the optimal composition shifts to a balanced Ta/Mo ratio (TM7.5–7.5). This adaptability stems from a dynamic interplay where Mo's chemical stabilization is amplified to counter NH4Cl's complex acidic and ion-complexing attack. This study validates a pathway for designing advanced EHEAs, where tailored synergistic alloying counters specific environmental threats, boosting reliability for demanding applications.
传统的合金设计通常以单一的普遍最佳成分为目标。这种模式受到了（CoCrFeNi）85TaxMo15-x共晶高熵合金（EHEAs）的“威胁匹配”协同合金化策略的挑战，该合金通过真空电弧熔化制备，具有卓越的环境特定性能。系统调整Ta/Mo比可得到一种共晶（CoCrFeNi）85Ta5Mo10合金，其屈服强度为~ 1.7 GPa，断裂应变为31.7%。值得注意的是，耐腐蚀性随环境变化而变化。在0.6 M NaCl中，高ta合金（TM10-5）通过强大的Ta2O5屏障提供卓越的保护；在侵略性为0.6 M的NH4Cl中，最佳组成转变为平衡的Ta/Mo比（TM7.5-7.5）。这种适应性源于一种动态的相互作用，其中Mo的化学稳定性被放大以对抗NH4Cl的复杂酸性和离子络合攻击。该研究验证了设计先进EHEAs的途径，其中定制的协同合金可以应对特定的环境威胁，提高高要求应用的可靠性。
{"title":"Environment dependent Ta-Mo synergy toward eutectic high-entropy alloys with strength and tunable corrosion resistance","authors":"Jiajun Yuan , Zengmin Shi , Lei Dai , Xicong Ye , Long Xu , Junwen Gao , Panxing Liu","doi":"10.1016/j.intermet.2026.109180","DOIUrl":"10.1016/j.intermet.2026.109180","url":null,"abstract":"<div><div>Conventional alloy design often targets a single universally optimal composition. This paradigm is challenged by a ‘threat-matched’ synergistic alloying strategy in (CoCrFeNi)<sub>85</sub>Ta<sub><em>x</em></sub>Mo<sub>15-<em>x</em></sub> eutectic high-entropy alloys (EHEAs), prepared by vacuum arc melting, enabling remarkable environment-specific performance. Systematic tuning of the Ta/Mo ratio yields a eutectic (CoCrFeNi)<sub>85</sub>Ta<sub>5</sub>Mo<sub>10</sub> alloy with exceptional properties of ∼1.7 GPa yield strength and 31.7 % fracture strain. Notably, corrosion resistance shifts with environment. In 0.6 M NaCl, a high-Ta alloy (TM10-5) offers a superior protection via a robust Ta<sub>2</sub>O<sub>5</sub> barrier; in aggressive 0.6 M NH<sub>4</sub>Cl, the optimal composition shifts to a balanced Ta/Mo ratio (TM7.5–7.5). This adaptability stems from a dynamic interplay where Mo's chemical stabilization is amplified to counter NH<sub>4</sub>Cl's complex acidic and ion-complexing attack. This study validates a pathway for designing advanced EHEAs, where tailored synergistic alloying counters specific environmental threats, boosting reliability for demanding applications.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"191 ","pages":"Article 109180"},"PeriodicalIF":4.8,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075934","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 : 2026-01-28DOI: 10.1016/j.intermet.2026.109177
Nithin Joseph Reddy Sagili Arthur , Rae Eon Kim , Ana Martins , Hyoung Seop Kim , N. Schell , João Pedro Oliveira
Dissimilar fusion welding of a NiTi shape memory alloy and an AlCoCrFeNi2.1 eutectic high entropy alloy was performed using a niobium interlayer. The unique properties of these materials complement each other, potentially enabling hybrid structures for advanced applications and smart systems. Gas tungsten arc welding with an arc offset technique was employed to create a weld-braze joint at the NiTi-Nb interface while controlling the heat input. Comprehensive microstructural and phase analysis was carried out using optical and electron microscopy, synchrotron X-ray diffraction, and was further supplemented by thermodynamic simulations. Dissolution of the Nb interlayer altered the solidification pathways in the fusion zone, leading to the formation of topologically close-packed phases (including C14 Laves and σ) and Ti2Ni. Multiple interfacial reactions at the NiTi interface introduced significant strain, which increased hardness but also acted as stress concentrators during tensile loading. The addition of the niobium interlayer enabled the formation of a stable, crack-free joint, whereas welding without an interlayer resulted in catastrophic cracking.
{"title":"Gas tungsten arc welding of NiTi shape memory alloy and AlCoCrFeNi2.1 eutectic high entropy alloy using a niobium interlayer","authors":"Nithin Joseph Reddy Sagili Arthur , Rae Eon Kim , Ana Martins , Hyoung Seop Kim , N. Schell , João Pedro Oliveira","doi":"10.1016/j.intermet.2026.109177","DOIUrl":"10.1016/j.intermet.2026.109177","url":null,"abstract":"<div><div>Dissimilar fusion welding of a NiTi shape memory alloy and an AlCoCrFeNi<sub>2.1</sub> eutectic high entropy alloy was performed using a niobium interlayer. The unique properties of these materials complement each other, potentially enabling hybrid structures for advanced applications and smart systems. Gas tungsten arc welding with an arc offset technique was employed to create a weld-braze joint at the NiTi-Nb interface while controlling the heat input. Comprehensive microstructural and phase analysis was carried out using optical and electron microscopy, synchrotron X-ray diffraction, and was further supplemented by thermodynamic simulations. Dissolution of the Nb interlayer altered the solidification pathways in the fusion zone, leading to the formation of topologically close-packed phases (including C14 Laves and σ) and Ti<sub>2</sub>Ni. Multiple interfacial reactions at the NiTi interface introduced significant strain, which increased hardness but also acted as stress concentrators during tensile loading. The addition of the niobium interlayer enabled the formation of a stable, crack-free joint, whereas welding without an interlayer resulted in catastrophic cracking.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"191 ","pages":"Article 109177"},"PeriodicalIF":4.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075911","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 : 2026-01-28DOI: 10.1016/j.intermet.2026.109176
Qinying Wang , Yiping Wu , Yuhui Song , Daichen Li , Yuchen Xi , Yangfei Zhang , Shulin Bai
Harsh tribocorrosion conditions require enhanced corrosion resistance and hardness of metallic components. Data-driven approaches and the vast compositional space of high-entropy alloys (HEAs) offer the potential to efficiently discover novel HEAs combining high corrosion resistance, high hardness, and economic viability. This study developed multiple machine learning (ML) models to predict the corrosion resistance (pitting potential, Ep) of HEAs, among which the XGBoost model demonstrated optimal performance (R2 = 0.86). Interpretation techniques including SHapley Additive exPlanation (SHAP), Individual Conditional Expectation (ICE), Accumulated Local Effect (ALE), and Partial Dependence Plots (PDP) elucidated the effects of compositional features on Ep and guided the selection of corrosion-resistant elements. Guided by hardness-oriented large lattice distortion and economic feasibility, the principal elements were identified for the target HEA. Inverse design via a genetic algorithm yielded the target composition of Fe19.5Ni20.5Cr31.5Mn7.5Ti21 (wt.%), with experimental verification confirming excellent corrosion resistance and high hardness, achieving Ep = 0.872 VSCE in a 3.5 wt% NaCl solution and a hardness of 815.9 HV. The alloy exhibits HCP and BCC phases. The corrosion resistance is attributed to the passivation effect of Cr, while the high hardness results from the significant lattice distortion induced by Ti addition.
{"title":"Development of a high-entropy alloy with both high corrosion resistance and hardness by data-driven intelligent design methods","authors":"Qinying Wang , Yiping Wu , Yuhui Song , Daichen Li , Yuchen Xi , Yangfei Zhang , Shulin Bai","doi":"10.1016/j.intermet.2026.109176","DOIUrl":"10.1016/j.intermet.2026.109176","url":null,"abstract":"<div><div>Harsh tribocorrosion conditions require enhanced corrosion resistance and hardness of metallic components. Data-driven approaches and the vast compositional space of high-entropy alloys (HEAs) offer the potential to efficiently discover novel HEAs combining high corrosion resistance, high hardness, and economic viability. This study developed multiple machine learning (ML) models to predict the corrosion resistance (pitting potential, <em>E</em><sub><em>p</em></sub>) of HEAs, among which the XGBoost model demonstrated optimal performance (R<sup>2</sup> = 0.86). Interpretation techniques including SHapley Additive exPlanation (SHAP), Individual Conditional Expectation (ICE), Accumulated Local Effect (ALE), and Partial Dependence Plots (PDP) elucidated the effects of compositional features on <em>E</em><sub><em>p</em></sub> and guided the selection of corrosion-resistant elements. Guided by hardness-oriented large lattice distortion and economic feasibility, the principal elements were identified for the target HEA. Inverse design via a genetic algorithm yielded the target composition of Fe<sub>19.5</sub>Ni<sub>20.5</sub>Cr<sub>31.5</sub>Mn<sub>7.5</sub>Ti<sub>21</sub> (wt.%), with experimental verification confirming excellent corrosion resistance and high hardness, achieving <em>E</em><sub><em>p</em></sub> = 0.872 V<sub>SCE</sub> in a 3.5 wt% NaCl solution and a hardness of 815.9 HV. The alloy exhibits HCP and BCC phases. The corrosion resistance is attributed to the passivation effect of Cr, while the high hardness results from the significant lattice distortion induced by Ti addition.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"191 ","pages":"Article 109176"},"PeriodicalIF":4.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075912","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 : 2026-01-27DOI: 10.1016/j.intermet.2026.109172
Yuning Wang , Xinguang Wang , Zihao Tan , Yongmei Li , Haibing Tan , Yunling Du , Yan Tao , Yanhong Yang , Jide Liu , Jinguo Li , Yizhou Zhou , Xiaofeng Sun
The creep behavior and microscopic deformation mechanisms of a fourth-generation Ru-containing Ni-based single crystal superalloy were investigated at intermediate temperature of 850 °C under high applied stresses of 620, 700, and 750 MPa. SEM and TEM analyses showed that the alloy exhibited a mixed fracture mode mainly composed of micropore coalescence and shear. The γ′ precipitates exhibited stress-dependent rafting, forming relatively regular rafts at lower stress and elongated structures parallel to the loading direction at higher stresses. The alloy shown a low stacking fault energy (SFE) in the γ matrix, as evidenced by a high density of extended stacking faults (SFs) and dislocation configurations in both the γ channels and the γ′ phase. With increasing stress, a/3<112> leading Shockley partial dislocations were activated to shear the γ′ phase and generate SFs. The resulting SF locks and dislocation pile-ups impeded subsequent dislocation motion and provided additional resistance to creep. These low-SFE–controlled dislocation mechanisms govern the creep deformation of this fourth-generation alloy in the intermediate temperature high stress regime and provide mechanistic guidance for the design of high performance single crystal superalloys in service conditions.
{"title":"Creep behavior and deformation mechanisms of a fourth-generation Ni-based single crystal superalloy at intermediate temperatures","authors":"Yuning Wang , Xinguang Wang , Zihao Tan , Yongmei Li , Haibing Tan , Yunling Du , Yan Tao , Yanhong Yang , Jide Liu , Jinguo Li , Yizhou Zhou , Xiaofeng Sun","doi":"10.1016/j.intermet.2026.109172","DOIUrl":"10.1016/j.intermet.2026.109172","url":null,"abstract":"<div><div>The creep behavior and microscopic deformation mechanisms of a fourth-generation Ru-containing Ni-based single crystal superalloy were investigated at intermediate temperature of 850 °C under high applied stresses of 620, 700, and 750 MPa. SEM and TEM analyses showed that the alloy exhibited a mixed fracture mode mainly composed of micropore coalescence and shear. The γ′ precipitates exhibited stress-dependent rafting, forming relatively regular rafts at lower stress and elongated structures parallel to the loading direction at higher stresses. The alloy shown a low stacking fault energy (SFE) in the γ matrix, as evidenced by a high density of extended stacking faults (SFs) and dislocation configurations in both the γ channels and the γ′ phase. With increasing stress, a/3<112> leading Shockley partial dislocations were activated to shear the γ′ phase and generate SFs. The resulting SF locks and dislocation pile-ups impeded subsequent dislocation motion and provided additional resistance to creep. These low-SFE–controlled dislocation mechanisms govern the creep deformation of this fourth-generation alloy in the intermediate temperature high stress regime and provide mechanistic guidance for the design of high performance single crystal superalloys in service conditions.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"191 ","pages":"Article 109172"},"PeriodicalIF":4.8,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075908","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 : 2026-01-26DOI: 10.1016/j.intermet.2026.109163
He Qu , Wei Zhang , Qingchun Xiang , Yinglei Ren , Weidong Liu , Keqiang Qiu
Lattice distortion is a critical structural characteristic in alloys that significantly influences their mechanical properties. This work employs density functional theory (DFT) and empirical electron theory of solids and molecules (EET) to investigate the lattice distortion in the CoCrFeNiMn alloy and its sub-alloys (such as CoNi, FeNi, CoFeNi, CoNiMn, FeNiMn, CoCrNi, CoFeNiMn, CoCrFeNi, and CoCrNiMn). The results show that the number of covalent electrons in valence electrons is a key factor affecting lattice distortion. Specifically, a smaller number of covalent electrons in a bond weakens the interatomic force, facilitating atomic displacement from equilibrium positions and thereby enhancing lattice distortion. Among the studied elements, Cr causes the most significant local bond length fluctuation and the largest lattice distortion, followed by Mn, Fe, Co and Ni. Mechanical property tests were conducted on the CoNi, CoNiMn, and CoCrNi alloys with significant differences in lattice distortion. The results indicate that the variation trend of the yield strength (53, 68 and 92 MPa) aligns with that of the lattice distortion (0.73 %, 0.94 % and 1.37 %) for the three alloys.
{"title":"Unraveling the origin of lattice distortion in Co-Cr-Fe-Ni-Mn system via electronic structure analysis","authors":"He Qu , Wei Zhang , Qingchun Xiang , Yinglei Ren , Weidong Liu , Keqiang Qiu","doi":"10.1016/j.intermet.2026.109163","DOIUrl":"10.1016/j.intermet.2026.109163","url":null,"abstract":"<div><div>Lattice distortion is a critical structural characteristic in alloys that significantly influences their mechanical properties. This work employs density functional theory (DFT) and empirical electron theory of solids and molecules (EET) to investigate the lattice distortion in the CoCrFeNiMn alloy and its sub-alloys (such as CoNi, FeNi, CoFeNi, CoNiMn, FeNiMn, CoCrNi, CoFeNiMn, CoCrFeNi, and CoCrNiMn). The results show that the number of covalent electrons in valence electrons is a key factor affecting lattice distortion. Specifically, a smaller number of covalent electrons in a bond weakens the interatomic force, facilitating atomic displacement from equilibrium positions and thereby enhancing lattice distortion. Among the studied elements, Cr causes the most significant local bond length fluctuation and the largest lattice distortion, followed by Mn, Fe, Co and Ni. Mechanical property tests were conducted on the CoNi, CoNiMn, and CoCrNi alloys with significant differences in lattice distortion. The results indicate that the variation trend of the yield strength (53, 68 and 92 MPa) aligns with that of the lattice distortion (0.73 %, 0.94 % and 1.37 %) for the three alloys.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"191 ","pages":"Article 109163"},"PeriodicalIF":4.8,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075909","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 : 2026-01-24DOI: 10.1016/j.intermet.2026.109158
Wei Wang , Zhou Li , Mingzhen Han , Yi Zhang , Wangzhong Mu , Nan Wang , Wenda Zhang , Zhankun Weng
This study investigates the effects of vanadium (V), niobium (Nb), and tantalum (Ta) doping on the microstructure, electrochemical corrosion behavior, and mechanical properties of cobalt-based high-entropy alloys (HEAs). Guided by CALPHAD (CALculation of PHAse Diagrams) thermodynamic calculations, a series of alloys were designed and synthesized via vacuum induction melting, followed by homogenization and cryogenic treatments. Microstructural analyses revealed that V promotes the formation of σ phase, while Nb and Ta facilitate the precipitation of Laves phases within the face-centered cubic (fcc) matrix. Cryogenic treatment further refined the microstructure and promoted the formation of a hexagonal close-packed (hcp) martensite phase. Electrochemical tests in 3.5 wt% NaCl solution demonstrated that all doped alloys exhibit excellent passivation behavior, with the Nb-doped variant showing the highest corrosion resistance due to its enhanced charge transfer resistance and more stable passive film enriched with Cr2O3, CoCr2O4, CoFe2O4, and V/Nb/Ta oxides. Electrochemical corrosion tests and Pourbaix diagram analysis clarified the alloys' resistance to localized corrosion. Mechanical characterization indicated that precipitation hardening and deformation-induced martensitic transformation (TRIP effect) contribute to an outstanding strength-ductility balance. These results highlight the potential of V-, Nb-, and Ta-doped cobalt-based HEAs as advanced metallic materials for demanding applications in extreme environments.
{"title":"CALPHAD-guided design of corrosion-resistant cobalt-based high-entropy alloys with strength-ductility synergy achieved through V, Nb, and Ta alloying","authors":"Wei Wang , Zhou Li , Mingzhen Han , Yi Zhang , Wangzhong Mu , Nan Wang , Wenda Zhang , Zhankun Weng","doi":"10.1016/j.intermet.2026.109158","DOIUrl":"10.1016/j.intermet.2026.109158","url":null,"abstract":"<div><div>This study investigates the effects of vanadium (V), niobium (Nb), and tantalum (Ta) doping on the microstructure, electrochemical corrosion behavior, and mechanical properties of cobalt-based high-entropy alloys (HEAs). Guided by CALPHAD (CALculation of PHAse Diagrams) thermodynamic calculations, a series of alloys were designed and synthesized via vacuum induction melting, followed by homogenization and cryogenic treatments. Microstructural analyses revealed that V promotes the formation of σ phase, while Nb and Ta facilitate the precipitation of Laves phases within the face-centered cubic (fcc) matrix. Cryogenic treatment further refined the microstructure and promoted the formation of a hexagonal close-packed (hcp) martensite phase. Electrochemical tests in 3.5 wt% NaCl solution demonstrated that all doped alloys exhibit excellent passivation behavior, with the Nb-doped variant showing the highest corrosion resistance due to its enhanced charge transfer resistance and more stable passive film enriched with Cr<sub>2</sub>O<sub>3</sub>, CoCr<sub>2</sub>O<sub>4</sub>, CoFe<sub>2</sub>O<sub>4</sub>, and V/Nb/Ta oxides. Electrochemical corrosion tests and Pourbaix diagram analysis clarified the alloys' resistance to localized corrosion. Mechanical characterization indicated that precipitation hardening and deformation-induced martensitic transformation (TRIP effect) contribute to an outstanding strength-ductility balance. These results highlight the potential of V-, Nb-, and Ta-doped cobalt-based HEAs as advanced metallic materials for demanding applications in extreme environments.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"191 ","pages":"Article 109158"},"PeriodicalIF":4.8,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037025","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 : 2026-01-23DOI: 10.1016/j.intermet.2026.109178
Guanghao Gong , Zifan Wang , Longjie Zhao , Fei Weng , Huijun Yu , Zhihuan Zhao , Chuanzhong Chen
In this study, the effect of heat-treatment on the microstructures, mechanical properties, and high-temperature oxidation behavior of Hastelloy X fabricated by laser directed energy deposition was investigated. The solution treatment dissolved Laves phases and increased the grain size resulting in a homogenized γ-matrix with improved ductility but reduced strength. The subsequent aging treatment precipitated fine M23C6, restoring strength and decreasing ductility. The oxidation tests conducted at 1000 °C up to 100 h revealed that the samples after heat-treatment exhibited a superior resistance due to the oxide consisted of continuous and dense Cr2O3 with outer spinels and less spallation behavior. The results reveal that the heat-treatment can achieve a balance between mechanical properties and oxidation resistance by tailoring the microstructures.
{"title":"Effect of heat-treatment on mechanical properties and high-temperature oxidation behavior of Hastelloy X fabricated by laser directed energy deposition","authors":"Guanghao Gong , Zifan Wang , Longjie Zhao , Fei Weng , Huijun Yu , Zhihuan Zhao , Chuanzhong Chen","doi":"10.1016/j.intermet.2026.109178","DOIUrl":"10.1016/j.intermet.2026.109178","url":null,"abstract":"<div><div>In this study, the effect of heat-treatment on the microstructures, mechanical properties, and high-temperature oxidation behavior of Hastelloy X fabricated by laser directed energy deposition was investigated. The solution treatment dissolved Laves phases and increased the grain size resulting in a homogenized γ-matrix with improved ductility but reduced strength. The subsequent aging treatment precipitated fine M<sub>23</sub>C<sub>6</sub>, restoring strength and decreasing ductility. The oxidation tests conducted at 1000 °C up to 100 h revealed that the samples after heat-treatment exhibited a superior resistance due to the oxide consisted of continuous and dense Cr<sub>2</sub>O<sub>3</sub> with outer spinels and less spallation behavior. The results reveal that the heat-treatment can achieve a balance between mechanical properties and oxidation resistance by tailoring the microstructures.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"191 ","pages":"Article 109178"},"PeriodicalIF":4.8,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037024","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 : 2026-01-23DOI: 10.1016/j.intermet.2026.109164
Shuanglei Li , Siyu Yuan , Peng Wu , Su-Young Kim , Tae-Hyun Nam , Jong-Taek Yeom , Xu Wang
Toxic element-free β-type Ti-Zr-Nb-Sn shape memory alloys offer exceptional potential for advanced biomedical applications, yet achieving optimal superelasticity requires precise control of alloy composition and microstructure, which is particularly sensitive to the interplay between Sn content and annealing conditions. This study systematically investigates the effects of Sn content (3.5–5 at%) and annealing temperature (850–1100 °C) on the microstructure, texture evolution, and superelastic behavior of cost-effective Ti-20Zr-9Nb-xSn alloys. A strong {001}β<110>β recrystallization texture, vital for maximizing the transformation strain of β → α″, is found to develop under a precise synergy of Sn content and annealing treatment. We found that its formation is governed by two factors: (i) a low valence electron-to-atom (e/a) ratio (4.0–4.15), which ensures low β-phase stability and promotes unconventional deformation textures, and (ii) the achievement of a critical, composition-dependent β grain size during annealing. Excessive Sn promotes Zr5Sn3-type second phase formation, which retards recrystallization via Zener pinning, thereby weakening {001}β<110>β texture development and necessitating higher annealing temperatures. The Ti-20Zr-9Nb-5Sn alloy annealed at 950 °C exhibited a maximum recovery strain of 4.8 %, demonstrating that tailored thermomechanical processing can simultaneously optimize microstructure and transformation conditions for optimizing superelasticity. Above all, this study, for the first time, proposes a new superelastic region in the conventional diagram for predicting novel superelastic β Ti-Zr-based alloys. The presented linking of Sn content and annealing temperature to functional performance establishes fundamental guidelines for optimizing alloy composition and thermomechanical processing, providing a foundation for developing high-performance Ti-Zr-Nb-Sn superelastic alloys for potential biomedical applications.
{"title":"Insight into how Sn content and annealing temperature dictate microstructural characteristics to regulate the superelasticity in Ti-Zr-Nb-Sn alloys","authors":"Shuanglei Li , Siyu Yuan , Peng Wu , Su-Young Kim , Tae-Hyun Nam , Jong-Taek Yeom , Xu Wang","doi":"10.1016/j.intermet.2026.109164","DOIUrl":"10.1016/j.intermet.2026.109164","url":null,"abstract":"<div><div>Toxic element-free β-type Ti-Zr-Nb-Sn shape memory alloys offer exceptional potential for advanced biomedical applications, yet achieving optimal superelasticity requires precise control of alloy composition and microstructure, which is particularly sensitive to the interplay between Sn content and annealing conditions. This study systematically investigates the effects of Sn content (3.5–5 at%) and annealing temperature (850–1100 °C) on the microstructure, texture evolution, and superelastic behavior of cost-effective Ti-20Zr-9Nb-xSn alloys. A strong {001}<sub>β</sub><110><sub>β</sub> recrystallization texture, vital for maximizing the transformation strain of β → α″, is found to develop under a precise synergy of Sn content and annealing treatment. We found that its formation is governed by two factors: (i) a low valence electron-to-atom (e/a) ratio (4.0–4.15), which ensures low β-phase stability and promotes unconventional deformation textures, and (ii) the achievement of a critical, composition-dependent β grain size during annealing. Excessive Sn promotes Zr<sub>5</sub>Sn<sub>3</sub>-type second phase formation, which retards recrystallization via Zener pinning, thereby weakening {001}<sub>β</sub><110><sub>β</sub> texture development and necessitating higher annealing temperatures. The Ti-20Zr-9Nb-5Sn alloy annealed at 950 °C exhibited a maximum recovery strain of 4.8 %, demonstrating that tailored thermomechanical processing can simultaneously optimize microstructure and transformation conditions for optimizing superelasticity. Above all, this study, for the first time, proposes a new superelastic region in the conventional <span><math><mrow><mover><msub><mi>B</mi><mi>o</mi></msub><mo>‾</mo></mover><mo>−</mo><mover><msub><mi>M</mi><mi>d</mi></msub><mo>‾</mo></mover></mrow></math></span> diagram for predicting novel superelastic β Ti-Zr-based alloys. The presented linking of Sn content and annealing temperature to functional performance establishes fundamental guidelines for optimizing alloy composition and thermomechanical processing, providing a foundation for developing high-performance Ti-Zr-Nb-Sn superelastic alloys for potential biomedical applications.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"191 ","pages":"Article 109164"},"PeriodicalIF":4.8,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146015846","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 : 2026-01-23DOI: 10.1016/j.intermet.2026.109174
Hang Cai , Zhitao Li , Yujun Sun , Tianren Qu , Qi Han , Yunsheng Wu , Xianjun Guan , Le Zhao , Jieshan Hou , Lan-zhang Zhou
The effect of various Al/Ti ratio on microstructural characteristics and creep behavior at 1100 °C/100 MPa in low-density Ni3Al-based single crystal superalloys was systematically investigated through multi-technique characterization. Quantitative analysis revealed that a direct correlation between increasing Al/Ti ratios progressively adjusted from 0.54 through 1.00 to 1.86 and corresponding enhancement in γ′ phase volume fraction from 67.9 % to 75.6 % and ultimately 80.4 %. This compositional modification concurrently induces three critical microstructural transformations: first, refinement of γ′ precipitates into cubic morphology with the shape factors closer to 1.41; second, narrowing of γ channels from 96.5 nm to 56.0 nm and then to 45.6 nm; third, preferential partitioning of large-radius elements including Cr and W into γ phases, driving γ/γ′ lattice misfit towards increased negative values from −0.127 % to −0.185 % and finally −0.350 %. Contrary to conventional Ti-dominated γ′ paradigm, the results in this study demonstrated superior creep performance in higher Al/Ti ratio alloys. A variety of strengthening mechanisms related to microstructures are analyzed, and the results reveal that, enhanced solid-solution strengthening in the γ phase arises from Al/Ti ratio-controlled partitioning of Mo, W and Cr solutes. Finer γ′ precipitate, higher γ′ volume fraction and narrow γ channel width induced by increasing Al/Ti ratio collectively elevate the threshold stress for dislocation climb from 24 MPa to 86 MPa. Additionally, a well-developed rafting of γ′ phase was observed in higher Al/Ti ratio alloy after creep, which also plays a role in reducing the creep rate. Finally, more completed and denser dislocations network are located at the γ/γ′ interface in the higher Al/Ti ratio alloy, effectively impeding dislocation from cutting into the γ′ precipitates, thereby reducing the minimum creep rate from 1.46 × 10−5 %‧s−1 to 1.25 × 10−6 %‧s−1, and the creep life extension up to 138.08 h. This performance represents a significant improvement over reported values for low-density superalloys.
{"title":"Unveiling the influence of Al/Ti ratio on microstructural evolution and creep behaviors in low-density Ni3Al-based SX superalloys","authors":"Hang Cai , Zhitao Li , Yujun Sun , Tianren Qu , Qi Han , Yunsheng Wu , Xianjun Guan , Le Zhao , Jieshan Hou , Lan-zhang Zhou","doi":"10.1016/j.intermet.2026.109174","DOIUrl":"10.1016/j.intermet.2026.109174","url":null,"abstract":"<div><div>The effect of various Al/Ti ratio on microstructural characteristics and creep behavior at 1100 °C/100 MPa in low-density Ni<sub>3</sub>Al-based single crystal superalloys was systematically investigated through multi-technique characterization. Quantitative analysis revealed that a direct correlation between increasing Al/Ti ratios progressively adjusted from 0.54 through 1.00 to 1.86 and corresponding enhancement in γ′ phase volume fraction from 67.9 % to 75.6 % and ultimately 80.4 %. This compositional modification concurrently induces three critical microstructural transformations: first, refinement of γ′ precipitates into cubic morphology with the shape factors closer to 1.41; second, narrowing of γ channels from 96.5 nm to 56.0 nm and then to 45.6 nm; third, preferential partitioning of large-radius elements including Cr and W into γ phases, driving γ/γ′ lattice misfit towards increased negative values from −0.127 % to −0.185 % and finally −0.350 %. Contrary to conventional Ti-dominated γ′ paradigm, the results in this study demonstrated superior creep performance in higher Al/Ti ratio alloys. A variety of strengthening mechanisms related to microstructures are analyzed, and the results reveal that, enhanced solid-solution strengthening in the γ phase arises from Al/Ti ratio-controlled partitioning of Mo, W and Cr solutes. Finer γ′ precipitate, higher γ′ volume fraction and narrow γ channel width induced by increasing Al/Ti ratio collectively elevate the threshold stress for dislocation climb from 24 MPa to 86 MPa. Additionally, a well-developed rafting of γ′ phase was observed in higher Al/Ti ratio alloy after creep, which also plays a role in reducing the creep rate. Finally, more completed and denser dislocations network are located at the γ/γ′ interface in the higher Al/Ti ratio alloy, effectively impeding dislocation from cutting into the γ′ precipitates, thereby reducing the minimum creep rate from 1.46 × 10<sup>−5</sup> %‧s<sup>−1</sup> to 1.25 × 10<sup>−6</sup> %‧s<sup>−1</sup>, and the creep life extension up to 138.08 h. This performance represents a significant improvement over reported values for low-density superalloys.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"191 ","pages":"Article 109174"},"PeriodicalIF":4.8,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146015847","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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