Using pulse electrodeposition method on copper substrates, AlFeCrNiTi high entropy alloy (HEA) coatings were successfully applied with various concentrations of silicon carbide (0, 10, 15 and 20 g/L) in the coating bath as reinforcement. Various techniques were used to investigate the created structure and its properties, including morphology, chemical composition, phase analysis, microhardness, corrosion, and wear. In the presence of silicon carbide particles, the coatings had a spherical morphology. The formation of HEA was confirmed by EDS, XRD, and thermodynamic calculations, which showed that the solid solution formed without silicon carbide and with silicon carbide was FCC + BCC and BCC respectively. Furthermore, the results of mechanical and corrosion properties showed that the fineness of the grains improved microhardness and wear resistance, and due to the formation of a continuous passive layer caused by silicon carbide powder, the corrosion current density in 3.5 wt% NaCl solution decreased to 0.79 A/cm2 and the charge transfer resistance increased to 6810 Ω cm2. Also, the sample with a concentration of 20 g/L of silicon carbide in the coating bath has better mechanical and corrosion properties than other samples.
{"title":"SiC incorporation effects on AlFeCrNiTi high entropy alloy morphology, mechanical and corrosion properties","authors":"Zahra Shojaei, Gholam Reza Khayati, Esmaeel Darezereshki","doi":"10.1016/j.intermet.2024.108583","DOIUrl":"10.1016/j.intermet.2024.108583","url":null,"abstract":"<div><div>Using pulse electrodeposition method on copper substrates, AlFeCrNiTi high entropy alloy (HEA) coatings were successfully applied with various concentrations of silicon carbide (0, 10, 15 and 20 g/L) in the coating bath as reinforcement. Various techniques were used to investigate the created structure and its properties, including morphology, chemical composition, phase analysis, microhardness, corrosion, and wear. In the presence of silicon carbide particles, the coatings had a spherical morphology. The formation of HEA was confirmed by EDS, XRD, and thermodynamic calculations, which showed that the solid solution formed without silicon carbide and with silicon carbide was FCC + BCC and BCC respectively. Furthermore, the results of mechanical and corrosion properties showed that the fineness of the grains improved microhardness and wear resistance, and due to the formation of a continuous passive layer caused by silicon carbide powder, the corrosion current density in 3.5 wt% NaCl solution decreased to 0.79 A/cm<sup>2</sup> and the charge transfer resistance increased to 6810 Ω cm<sup>2</sup>. Also, the sample with a concentration of 20 g/L of silicon carbide in the coating bath has better mechanical and corrosion properties than other samples.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"177 ","pages":"Article 108583"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095883","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 : 2025-02-01DOI: 10.1016/j.intermet.2024.108600
M. Torabi-Parizi
Medium/high entropy alloy (M/HEA) system compositions are promising in wear resistance with comprehensive mechanical performance to meet the demands of practical engineering and technological applications as a multi-functional material. Nevertheless, for nano/ultrafine grained M/HEAs, there is still rather limited consideration of the friction and wear performance. In the current work, we present a strategy to develop a spark plasma sintered (SPSed) (CoCrFeNi)84(AlTi)16 M/HEAs with low density, strength-plasticity synergy and excellent wear resistance via adjusting the heterogeneous bimodal and nanocrystalline structure of coupled medium/high entropy solid solution phases with proximate equal volume fraction in the presence of multicomponent submicron/nanometer intermetallic phases. The multiple scales-component-phase-driven structure of the (CoCrFeNi)84(AlTi)16 M/HEA systems results in superior mechanical properties for the 3 M/HEA system, where the micro hardness value, compressive yield strength (CYS), the ultimate compressive strength (UCS), the fracture strain (FS) and the specific yield strength are obtained about 676 HV, 1730 MPa, 2095 MPa, 11.5 % and 0.238 GPa cm3/g, respectively. Low coefficient of friction (low COF) of 0.17 and wear rate (WR) of 0.1 × 10−5 mm3N−1m−1 are achieved for the 3 M/HEA system, which are much lower than the reported M/HEAs and traditional wear resistance alloy. It is affected by synergy effect of hardness via the BCC phase, work hardenability and plastic deformation of FCC phase. For the 3 M/HEA system, the wear morphology is clearly detected as a smoother surface with the shallower grooves, representing that the main wear mechanism is an abrasive wear. Therefore, developing similar multiple scales-component-phase-driven structures may open an avenue for further optimization of the mechanical/wear performance of the M/HEA systems.
{"title":"Bimodal structure, strength-plasticity synergy and exceptional wear behavior in the spark plasma sintered (CoCrFeNi)84(AlTi)16 medium/high entropy alloy systems","authors":"M. Torabi-Parizi","doi":"10.1016/j.intermet.2024.108600","DOIUrl":"10.1016/j.intermet.2024.108600","url":null,"abstract":"<div><div>Medium/high entropy alloy (M/HEA) system compositions are promising in wear resistance with comprehensive mechanical performance to meet the demands of practical engineering and technological applications as a multi-functional material. Nevertheless, for nano/ultrafine grained M/HEAs, there is still rather limited consideration of the friction and wear performance. In the current work, we present a strategy to develop a spark plasma sintered (SPSed) (CoCrFeNi)<sub>84</sub>(AlTi)<sub>16</sub> M/HEAs with low density, strength-plasticity synergy and excellent wear resistance via adjusting the heterogeneous bimodal and nanocrystalline structure of coupled medium/high entropy solid solution phases with proximate equal volume fraction in the presence of multicomponent submicron/nanometer intermetallic phases. The multiple scales-component-phase-driven structure of the (CoCrFeNi)<sub>84</sub>(AlTi)<sub>16</sub> M/HEA systems results in superior mechanical properties for the 3 M/HEA system, where the micro hardness value, compressive yield strength (CYS), the ultimate compressive strength (UCS), the fracture strain (FS) and the specific yield strength are obtained about 676 HV, 1730 MPa, 2095 MPa, 11.5 % and 0.238 GPa cm<sup>3</sup>/g, respectively. Low coefficient of friction (low COF) of 0.17 and wear rate (WR) of 0.1 × 10<sup>−5</sup> mm<sup>3</sup>N<sup>−1</sup>m<sup>−1</sup> are achieved for the 3 M/HEA system, which are much lower than the reported M/HEAs and traditional wear resistance alloy. It is affected by synergy effect of hardness via the BCC phase, work hardenability and plastic deformation of FCC phase. For the 3 M/HEA system, the wear morphology is clearly detected as a smoother surface with the shallower grooves, representing that the main wear mechanism is an abrasive wear. Therefore, developing similar multiple scales-component-phase-driven structures may open an avenue for further optimization of the mechanical/wear performance of the M/HEA systems.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"177 ","pages":"Article 108600"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095893","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 : 2025-02-01DOI: 10.1016/j.intermet.2024.108591
Jianxiang Luo , Haoyu Xie , Bojing Guo , Zhongsheng Yang , Zhijia Zhang , Feng He
The γ′ precipitates have extensively enhanced the yield strength of NiCoCr-based medium entropy alloys (MEAs). However, further improvement is challenging since the precipitates’ volume fraction and size, which are currently used to tune the strengthening effect, have reached an optimal limit. Instead, here we propose to tune the composition of γ′ phase to overcome the above challenge. Through Ta microalloying, the precipitation strengthening effect of γ′ phase is enhanced by ∼34 % when the volume fraction and size of precipitates are almost the same. Detailed experimental and theoretical analysis evidenced the feasibility of our new strategy.
{"title":"Designing stronger γ′-hardened NiCoCr medium entropy alloys","authors":"Jianxiang Luo , Haoyu Xie , Bojing Guo , Zhongsheng Yang , Zhijia Zhang , Feng He","doi":"10.1016/j.intermet.2024.108591","DOIUrl":"10.1016/j.intermet.2024.108591","url":null,"abstract":"<div><div>The γ′ precipitates have extensively enhanced the yield strength of NiCoCr-based medium entropy alloys (MEAs). However, further improvement is challenging since the precipitates’ volume fraction and size, which are currently used to tune the strengthening effect, have reached an optimal limit. Instead, here we propose to tune the composition of γ′ phase to overcome the above challenge. Through Ta microalloying, the precipitation strengthening effect of γ′ phase is enhanced by ∼34 % when the volume fraction and size of precipitates are almost the same. Detailed experimental and theoretical analysis evidenced the feasibility of our new strategy.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"177 ","pages":"Article 108591"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095895","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 : 2025-02-01DOI: 10.1016/j.intermet.2024.108603
Zhonggang Han , Bingkun Wang , Tingting Zhai , Hao Sun , Tao Li , Zeming Yuan , Liwen Zhang , Yanghuan Zhang
Hydrogen storage using metal hydrides has a promising future due to its advantages of safety, efficiency, cheapness and cleanliness. In this experiment, the Ti1.08Zr0.1Y0.02Fe0.6Ni0.3Mn0.2+10 wt% M (V, Ni and Pd) composite alloy was produced by co-mingling highly active transition metals (V, Ni and Pd) with Ti1.08Zr0.1Y0.02Fe0.6Ni0.3Mn0.2 alloy through ball milling. Then, the activation properties, hydrogen absorption and desorption kinetics, and thermodynamic properties of the alloys were estimated. The results revealed that the catalyst ball milling not only decreased the size of the alloy particles and shortened the diffusion path but also generated new catalytically active centers and increased the diffusion channel of the alloy. The composite Pd ball-milled alloys exhibited superior activation behaviors and hydrogen absorption dynamics, reaching a hydrogen absorption saturation rate of 96.34 % at 100 s, without any activation incubation period at 150 °C, compared to the composite V and Ni ball-milled alloys, which achieved hydrogen absorption saturation rate of 93.34 % and 93.34 % at 100 s, respectively. Nevertheless, the composite V ball-milled alloy showed better hydrogen desorption kinetics and thermodynamic properties. Its hydrogen desorption saturation rate was 97.24 % at 90 °C, and the absolute values of the enthalpy change of its hydrogen absorption and desorption were the smallest of the three composite alloys, at 21.3 kJ‧mol−1 and 23.0 kJ‧mol−1, respectively. Since the electronegativity of V (1.63) was lower than those of Ni (1.91) and Pd (2.20), it is more favourable for reducing the bond energy of the Y–H bond.
{"title":"Influence on the microstructure and hydrogen storage properties of Y–TiFe-based composites with transition metals via mechanical milling","authors":"Zhonggang Han , Bingkun Wang , Tingting Zhai , Hao Sun , Tao Li , Zeming Yuan , Liwen Zhang , Yanghuan Zhang","doi":"10.1016/j.intermet.2024.108603","DOIUrl":"10.1016/j.intermet.2024.108603","url":null,"abstract":"<div><div>Hydrogen storage using metal hydrides has a promising future due to its advantages of safety, efficiency, cheapness and cleanliness. In this experiment, the Ti<sub>1.08</sub>Zr<sub>0.1</sub>Y<sub>0.02</sub>Fe<sub>0.6</sub>Ni<sub>0.3</sub>Mn<sub>0.2</sub>+10 wt% <em>M</em> (V, Ni and Pd) composite alloy was produced by co-mingling highly active transition metals (V, Ni and Pd) with Ti<sub>1.08</sub>Zr<sub>0.1</sub>Y<sub>0.02</sub>Fe<sub>0.6</sub>Ni<sub>0.3</sub>Mn<sub>0.2</sub> alloy through ball milling. Then, the activation properties, hydrogen absorption and desorption kinetics, and thermodynamic properties of the alloys were estimated. The results revealed that the catalyst ball milling not only decreased the size of the alloy particles and shortened the diffusion path but also generated new catalytically active centers and increased the diffusion channel of the alloy. The composite Pd ball-milled alloys exhibited superior activation behaviors and hydrogen absorption dynamics, reaching a hydrogen absorption saturation rate of 96.34 % at 100 s, without any activation incubation period at 150 °C, compared to the composite V and Ni ball-milled alloys, which achieved hydrogen absorption saturation rate of 93.34 % and 93.34 % at 100 s, respectively. Nevertheless, the composite V ball-milled alloy showed better hydrogen desorption kinetics and thermodynamic properties. Its hydrogen desorption saturation rate was 97.24 % at 90 °C, and the absolute values of the enthalpy change of its hydrogen absorption and desorption were the smallest of the three composite alloys, at 21.3 kJ‧mol<sup>−1</sup> and 23.0 kJ‧mol<sup>−1</sup>, respectively. Since the electronegativity of V (1.63) was lower than those of Ni (1.91) and Pd (2.20), it is more favourable for reducing the bond energy of the Y–H bond.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"177 ","pages":"Article 108603"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095386","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 : 2025-02-01DOI: 10.1016/j.intermet.2024.108589
V.O. Semin , R. Yamada , Y. Hamasaki , Y. Miyajima , K. Ishikawa , A. Watanabe , H. Kwon , H.S. Kim , H. Kato , D.V. Louzguine-Luzgin
In this study, we introduce a new series of Fe–Mn–Co–Ni–Cu–Al–C alloys that demonstrate tensile plasticity up to 10 % along with exceptionally high yield strength values reaching 1.5 GPa. These mechanical properties are achieved solely through standard technological processes, including homogenization, hot forging, cold rolling, and tempering/aging. This accomplishment is realized by leveraging the high-entropy/multiprinciple element approach, leading to the formation of a duplex-type cF4 and cI2 solid solution structure. The mechanical strengthening observed is a consequence of both dispersion strengthening with cI2 phase and deformation strengthening during the thermo-mechanical treatment applied. It is worth noting that this approach is versatile and can be extended to various other high-entropy-type alloys without strengthening intermetallic compounds. The effects of Cu addition, which is immiscible in Fe, on the resulting microstructure and oxidation heat resistance are also studied. Additionally, thermodynamic calculations are utilized to build phase diagrams for these multicomponent alloys.
{"title":"The effect of some late 3d transition metals additions to a Fe–Mn–Al–C alloy on the development of high-entropy alloys","authors":"V.O. Semin , R. Yamada , Y. Hamasaki , Y. Miyajima , K. Ishikawa , A. Watanabe , H. Kwon , H.S. Kim , H. Kato , D.V. Louzguine-Luzgin","doi":"10.1016/j.intermet.2024.108589","DOIUrl":"10.1016/j.intermet.2024.108589","url":null,"abstract":"<div><div>In this study, we introduce a new series of Fe–Mn–Co–Ni–Cu–Al–C alloys that demonstrate tensile plasticity up to 10 % along with exceptionally high yield strength values reaching 1.5 GPa. These mechanical properties are achieved solely through standard technological processes, including homogenization, hot forging, cold rolling, and tempering/aging. This accomplishment is realized by leveraging the high-entropy/multiprinciple element approach, leading to the formation of a duplex-type cF4 and cI2 solid solution structure. The mechanical strengthening observed is a consequence of both dispersion strengthening with cI2 phase and deformation strengthening during the thermo-mechanical treatment applied. It is worth noting that this approach is versatile and can be extended to various other high-entropy-type alloys without strengthening intermetallic compounds. The effects of Cu addition, which is immiscible in Fe, on the resulting microstructure and oxidation heat resistance are also studied. Additionally, thermodynamic calculations are utilized to build phase diagrams for these multicomponent alloys.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"177 ","pages":"Article 108589"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095389","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 : 2025-02-01DOI: 10.1016/j.intermet.2024.108588
Chengliang Qiu, Shuhong Liu, Yanwen Liu, Yong Du
Phase diagram of the Y-B system and isothermal sections of the Y-Fe-B system at 600 and 800 °C were investigated using X-ray diffraction (XRD), electron probe microanalysis (EPMA) and differential scanning calorimetry (DSC) on the annealed alloys. In the Y-B system, temperature of L↔(αY)+YB2 was determined to be 1294 °C. YB6 was confirmed to be a stoichiometric compound at 1000 °C. For the isothermal section of the Y-Fe-B system at 600 °C, five ternary compounds (τ1-τ4, τ6) and 10 three-phase regions were observed. But there were six ternary compounds (τ1-τ6) and 18 three-phase regions in the isothermal section at 800 °C. Ternary phases were measured to be stoichiometric compounds and the measured solubility of the third element in the binary phases was mostly below 0.5 at.% at both 600 and 800 °C.
{"title":"Phase equilibria in the Y-B and Y-Fe-B systems","authors":"Chengliang Qiu, Shuhong Liu, Yanwen Liu, Yong Du","doi":"10.1016/j.intermet.2024.108588","DOIUrl":"10.1016/j.intermet.2024.108588","url":null,"abstract":"<div><div>Phase diagram of the Y-B system and isothermal sections of the Y-Fe-B system at 600 and 800 °C were investigated using X-ray diffraction (XRD), electron probe microanalysis (EPMA) and differential scanning calorimetry (DSC) on the annealed alloys. In the Y-B system, temperature of L↔(αY)+YB<sub>2</sub> was determined to be 1294 °C. YB<sub>6</sub> was confirmed to be a stoichiometric compound at 1000 °C. For the isothermal section of the Y-Fe-B system at 600 °C, five ternary compounds (τ<sub>1</sub>-τ<sub>4</sub>, τ<sub>6</sub>) and 10 three-phase regions were observed. But there were six ternary compounds (τ<sub>1</sub>-τ<sub>6</sub>) and 18 three-phase regions in the isothermal section at 800 °C. Ternary phases were measured to be stoichiometric compounds and the measured solubility of the third element in the binary phases was mostly below 0.5 at.% at both 600 and 800 °C.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"177 ","pages":"Article 108588"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095882","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 : 2025-02-01DOI: 10.1016/j.intermet.2024.108604
Anjali Kanchi , Koteswararao V. Rajulapati , Vijayaraghavan Ganesan , Ravi C. Gundakaram
A detailed microstructural and structural study of the high-temperature oxidation behavior of refractory multicomponent alloys (RMCAs) with composition Nbx(MoTaW)(1-x) (x = 0.25, 0.4, 0.55, and 0.7 at%, designated as Nb0.25, Nb0.4, Nb0.55, and Nb0.7 respectively) was carried out as a function of Nb content at temperatures of 873K, 973K, and 1073K for durations up to 9h. Before the oxidation test, the RMCAs mentioned above had the single-phase BCC structure. Thermogravimetric curves demonstrated a weight gain with increase in temperature, time, and Nb concentration, showing that Nb0.7 has low oxidation resistance. The weight gain curves were fitted using a power law equation and it was observed that the data show a good fit for the linear oxidation behavior for all samples. Quantification of the activation energy for oxide formation revealed that a higher Nb content results in a lower activation energy, suggesting poor oxidation resistance. XRD patterns show that in the above oxidized RMCAs, simple oxides such as Nb2O5, Ta2O5, MoO3, and WO3 form at 873K since these have the lowest free energy of formation. At 973K and 1073K, these simple oxides react to produce complex oxides such as Nb2W3O14, Nb14W3O44, and Ta8W9O47, with a fraction of the simple oxides continuing to be present. As the temperature and Nb concentration increased, the surface morphology of RMCAs, as studied by SEM, revealed the presence of a discontinuous non-protective oxide layer with pores, bursts, nano-sized rod-shaped particles and cracks. In this study, Nb0.25 exhibits superior oxidation resistance as compared to other RMCAs.
{"title":"High-temperature oxidation behavior of Nbx(MoTaW)(1-x) (x = 0.25, 0.4, 0.55, and 0.7) refractory multicomponent alloys","authors":"Anjali Kanchi , Koteswararao V. Rajulapati , Vijayaraghavan Ganesan , Ravi C. Gundakaram","doi":"10.1016/j.intermet.2024.108604","DOIUrl":"10.1016/j.intermet.2024.108604","url":null,"abstract":"<div><div>A detailed microstructural and structural study of the high-temperature oxidation behavior of refractory multicomponent alloys (RMCAs) with composition Nb<sub>x</sub>(MoTaW)<sub>(1-x)</sub> (x = 0.25, 0.4, 0.55, and 0.7 at%, designated as Nb<sub>0.25,</sub> Nb<sub>0.4</sub>, Nb<sub>0.55</sub>, and Nb<sub>0.7</sub> respectively) was carried out as a function of Nb content at temperatures of 873K, 973K, and 1073K for durations up to 9h. Before the oxidation test, the RMCAs mentioned above had the single-phase BCC structure. Thermogravimetric curves demonstrated a weight gain with increase in temperature, time, and Nb concentration, showing that Nb<sub>0.7</sub> has low oxidation resistance. The weight gain curves were fitted using a power law equation and it was observed that the data show a good fit for the linear oxidation behavior for all samples. Quantification of the activation energy for oxide formation revealed that a higher Nb content results in a lower activation energy, suggesting poor oxidation resistance. XRD patterns show that in the above oxidized RMCAs, simple oxides such as Nb<sub>2</sub>O<sub>5</sub>, Ta<sub>2</sub>O<sub>5</sub>, MoO<sub>3</sub>, and WO<sub>3</sub> form at 873K since these have the lowest free energy of formation. At 973K and 1073K, these simple oxides react to produce complex oxides such as Nb<sub>2</sub>W<sub>3</sub>O<sub>14</sub>, Nb<sub>14</sub>W<sub>3</sub>O<sub>44</sub>, and Ta<sub>8</sub>W<sub>9</sub>O<sub>47</sub>, with a fraction of the simple oxides continuing to be present. As the temperature and Nb concentration increased, the surface morphology of RMCAs, as studied by SEM, revealed the presence of a discontinuous non-protective oxide layer with pores, bursts, nano-sized rod-shaped particles and cracks. In this study, Nb<sub>0.25</sub> exhibits superior oxidation resistance as compared to other RMCAs.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"177 ","pages":"Article 108604"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095892","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 : 2025-02-01DOI: 10.1016/j.intermet.2024.108606
Zhimin Yang , Shilin Feng , Chongxun Fang , Yongfu Cai , Zhenhua Han , Haimei Li , Ran Wei
We report a novel precipitation-strengthened Fe60Co20Ni15Mo5 medium entropy alloy (MEA). The MEA with single-phase BCC microstructure exhibits a high cryogenic tensile strength of ∼2.7 GPa, surpassing the state-of-the-art MEAs and high strength alloys. Besides, a unique dual-phase structure can be obtained by using the reverse process, that is, high-density spherical nanoprecipitates embedded within a BCC matrix and a minor presence of nanoprecipitates within the reverted FCC phase. Due to precipitation strengthening and transformation-induced plasticity effect, the dual-phase MEA exhibits outstanding cryogenic strength (∼2.2 GPa) and ductility (∼20 %) combinations.
{"title":"Ultrastrong and ductile Fe60Co20Ni15Mo5 medium-entropy alloy with high density nanoprecipitates","authors":"Zhimin Yang , Shilin Feng , Chongxun Fang , Yongfu Cai , Zhenhua Han , Haimei Li , Ran Wei","doi":"10.1016/j.intermet.2024.108606","DOIUrl":"10.1016/j.intermet.2024.108606","url":null,"abstract":"<div><div>We report a novel precipitation-strengthened Fe<sub>60</sub>Co<sub>20</sub>Ni<sub>15</sub>Mo<sub>5</sub> medium entropy alloy (MEA). The MEA with single-phase BCC microstructure exhibits a high cryogenic tensile strength of ∼2.7 GPa, surpassing the state-of-the-art MEAs and high strength alloys. Besides, a unique dual-phase structure can be obtained by using the reverse process, that is, high-density spherical nanoprecipitates embedded within a BCC matrix and a minor presence of nanoprecipitates within the reverted FCC phase. Due to precipitation strengthening and transformation-induced plasticity effect, the dual-phase MEA exhibits outstanding cryogenic strength (∼2.2 GPa) and ductility (∼20 %) combinations.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"177 ","pages":"Article 108606"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095387","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 great research breakthrough that occurred in materials science twenty years ago has brought new metallurgical alloy design principles and made it possible to create a unique kind of artificial materials – multi-element concentrated alloys. These complex solid solutions reveal unique crystalline structures and promising physical and chemical properties. All of these alloys are interesting for their functionality, but they have not yet been introduced into daily life due to their high price and complexity of production. It has recently been proposed that electrical resistance strain gauges and pressure sensors are among the most suitable practical applications in which these materials can be efficiently implemented. The further development of such alloys requires an improved understanding of the physical mechanisms behind high strain gauge sensitivity in these systems. This study focuses on a comprehensive analysis of the effects of pressure and uniaxial stress on electrical resistivity in the equiatomic TiZrHfTa high-entropy alloy, which is a typical representative of this family of materials. We measure electrical, magnetic, and thermal properties of the system and calculate its electronic structure and elastic constants to address issues associated with the strain and pressure effects, as well as evaluate the overall functionality for this kind of alloys in terms of possible passive electronic sensors. The tested alloy exhibits virtually temperature-independent resistivity and a superior strain gauge factor as large as 5.17. By analyzing the obtained data, we suggest that elastic anisotropy effects play a key role in the strain-sensitive behavior of refractory high-entropy alloys.
{"title":"Superior strain gauge sensitivity and elastic anisotropy in TiZrHfTa high entropy alloy","authors":"S.A. Uporov , I.V. Evdokimov , V.A. Sidorov , N.M. Chtchelkatchev , V.A. Bykov , E.V. Sterkhov , I.A. Balyakin , R.E. Ryltsev","doi":"10.1016/j.intermet.2024.108575","DOIUrl":"10.1016/j.intermet.2024.108575","url":null,"abstract":"<div><div>A great research breakthrough that occurred in materials science twenty years ago has brought new metallurgical alloy design principles and made it possible to create a unique kind of artificial materials – multi-element concentrated alloys. These complex solid solutions reveal unique crystalline structures and promising physical and chemical properties. All of these alloys are interesting for their functionality, but they have not yet been introduced into daily life due to their high price and complexity of production. It has recently been proposed that electrical resistance strain gauges and pressure sensors are among the most suitable practical applications in which these materials can be efficiently implemented. The further development of such alloys requires an improved understanding of the physical mechanisms behind high strain gauge sensitivity in these systems. This study focuses on a comprehensive analysis of the effects of pressure and uniaxial stress on electrical resistivity in the equiatomic TiZrHfTa high-entropy alloy, which is a typical representative of this family of materials. We measure electrical, magnetic, and thermal properties of the system and calculate its electronic structure and elastic constants to address issues associated with the strain and pressure effects, as well as evaluate the overall functionality for this kind of alloys in terms of possible passive electronic sensors. The tested alloy exhibits virtually temperature-independent resistivity and a superior strain gauge factor as large as 5.17. By analyzing the obtained data, we suggest that elastic anisotropy effects play a key role in the strain-sensitive behavior of refractory high-entropy alloys.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"177 ","pages":"Article 108575"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095385","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 : 2025-02-01DOI: 10.1016/j.intermet.2024.108605
Lin Wang, Chen Shen, Yuelong Zhang, Fang Li, Wenlu Zhou, Gang Ruan, Yuhan Ding, Kanglong Wu, Xueming Hua
Additive manufacturing (AM) has become an attractive method in fabricating TiAl alloys. In addition to the well-known anisotropy, additively manufactured TiAl alloys also exhibit heterogeneity. However, research in this area has been limited. This work systematically investigates the heterogeneity formation mechanism of the twin wire-directed energy deposition-arc produced TiAl alloy. The results show that the microstructure characteristics, such as the lamellar spacing (0.39 μm–0.56 μm), colony size (186 μm–232 μm), and α2 phase content (7 %–10 %), and microstructure degradation degree, present the tendency of increase from the upper to the lower part along the deposition direction, attributed to differences in the thermal cycle features experienced during AM. Consequently, its tensile strength (415.3 MPa–361 MPa) and elongation (0.54 %–0.38 %) also display a gradual decline from the upper to the lower part. This research contributes to a deeper understanding of the evolution of microstructure and the mechanical properties of additively manufactured TiAl alloys.
{"title":"The heterogeneity formation mechanism of twin wire-directed energy deposition-arc fabricated TiAl alloy","authors":"Lin Wang, Chen Shen, Yuelong Zhang, Fang Li, Wenlu Zhou, Gang Ruan, Yuhan Ding, Kanglong Wu, Xueming Hua","doi":"10.1016/j.intermet.2024.108605","DOIUrl":"10.1016/j.intermet.2024.108605","url":null,"abstract":"<div><div>Additive manufacturing (AM) has become an attractive method in fabricating TiAl alloys. In addition to the well-known anisotropy, additively manufactured TiAl alloys also exhibit heterogeneity. However, research in this area has been limited. This work systematically investigates the heterogeneity formation mechanism of the twin wire-directed energy deposition-arc produced TiAl alloy. The results show that the microstructure characteristics, such as the lamellar spacing (0.39 μm–0.56 μm), colony size (186 μm–232 μm), and α<sub>2</sub> phase content (7 %–10 %), and microstructure degradation degree, present the tendency of increase from the upper to the lower part along the deposition direction, attributed to differences in the thermal cycle features experienced during AM. Consequently, its tensile strength (415.3 MPa–361 MPa) and elongation (0.54 %–0.38 %) also display a gradual decline from the upper to the lower part. This research contributes to a deeper understanding of the evolution of microstructure and the mechanical properties of additively manufactured TiAl alloys.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"177 ","pages":"Article 108605"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095390","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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