Pub Date : 2025-12-26DOI: 10.1016/j.msea.2025.149683
Yuanpeng Yang , Linghui Hao , Yuting Gao , Chang Liu , Jiasheng Dong , Langhong Lou
The stress effects on the long-term microstructural stability of a polycrystalline Ni-based superalloy, K415, were systematically investigated. The comparison between stress-free aging and 60 MPa stress aging at 900 °C for up to 10,000 h focused particularly on the evolution of γ′ precipitates and grain boundary (GB) structure. The results indicate that applied stress accelerates γ′ coarsening kinetics in the early aging stage via the promotion of element diffusion by induced dislocations within the matrix. However, during the later aging stage, stress effects induce γ′ precipitate directional coalescence rather than non-directional coalescence, and facilitate additional Cr atoms into γ′ precipitates, which moderate precipitate agglomeration rate, thereby retarding γ′ degradation and improving microhardness. Furthermore, stress effects aggravate GB structure degradation by promoting dissolution of GB-M23C6, inducing stress concentration at GBs, and triggering interfacial debonding at the M23C6/γ′ incoherent interface, ultimately resulting in the formation of voids and microcracks. These findings offer valuable guidance for the precise control of γ′ precipitates and optimization of GB stability in novel polycrystalline superalloys, providing critical insights into the long-term microstructure evolution under near-service conditions.
{"title":"Stress and thermal coupling effect on microstructure evolution during long-term stress aging in K415 Ni-based superalloy","authors":"Yuanpeng Yang , Linghui Hao , Yuting Gao , Chang Liu , Jiasheng Dong , Langhong Lou","doi":"10.1016/j.msea.2025.149683","DOIUrl":"10.1016/j.msea.2025.149683","url":null,"abstract":"<div><div>The stress effects on the long-term microstructural stability of a polycrystalline Ni-based superalloy, K415, were systematically investigated. The comparison between stress-free aging and 60 MPa stress aging at 900 °C for up to 10,000 h focused particularly on the evolution of γ′ precipitates and grain boundary (GB) structure. The results indicate that applied stress accelerates γ′ coarsening kinetics in the early aging stage via the promotion of element diffusion by induced dislocations within the matrix. However, during the later aging stage, stress effects induce γ′ precipitate directional coalescence rather than non-directional coalescence, and facilitate additional Cr atoms into γ′ precipitates, which moderate precipitate agglomeration rate, thereby retarding γ′ degradation and improving microhardness. Furthermore, stress effects aggravate GB structure degradation by promoting dissolution of GB-M<sub>23</sub>C<sub>6</sub>, inducing stress concentration at GBs, and triggering interfacial debonding at the M<sub>23</sub>C<sub>6</sub>/γ′ incoherent interface, ultimately resulting in the formation of voids and microcracks. These findings offer valuable guidance for the precise control of γ′ precipitates and optimization of GB stability in novel polycrystalline superalloys, providing critical insights into the long-term microstructure evolution under near-service conditions.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"952 ","pages":"Article 149683"},"PeriodicalIF":7.0,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881542","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 : 2025-12-26DOI: 10.1016/j.msea.2025.149684
Qun Zhou , Xuan Zhao , Yongshun Fang , Xiuli Feng , Xin Yue , Peng He , Tiesong Lin
DZ406 superalloy is a second-generation Ni-based precipitation strengthened directionally solidified superalloy, and shows great potential as a repair material for gas turbine blades. However, no research has been reported on the microstructure and mechanical properties of laser direct energy deposited (LDED) DZ406 superalloy. This study systematically investigates the as-deposited and heat-treated states of LDED DZ406, focusing on microstructure evolution, elemental segregation, and high-temperature tensile/rupture properties. The as-deposited layer exhibited a dendritic structure with inter-dendritic segregation and an absence of γ′ strengthening phase. Stress-rupture tests revealed that creep cracks nucleated at inter-dendritic elemental segregation zones and propagated along these weakened regions until fracture failure. The application of a novel short-term high-temperature aging treatment eliminated the inter-dendritic elemental segregation and enhanced the γ′ phase strengthening effect in the LDED DZ406 superalloy. The average grain diameter decreased from 163 μm to 66.4 μm, and the texture intensity decreased from 240 to 110. Under the combined effects of grain boundary strengthening and aging strengthening, the creep rupture strength of the heat-treated deposit increased from 300 MPa to 320 MPa, and the creep rupture life increased from 130.08 h to 155.44 h. Quantitative calculations indicate that grain boundary and aging strengthening contributed an increase in creep rupture strength of approximately 23.76 MPa, which is consistent with the creep rupture test results. These findings provide a theoretical foundation for turbine blade repair using DZ406 LDED technology.
{"title":"Effects of heat treatment on microstructure, stress-rupture performance, and fracture failure behaviour of DZ406 superalloy fabricated by laser direct energy deposition","authors":"Qun Zhou , Xuan Zhao , Yongshun Fang , Xiuli Feng , Xin Yue , Peng He , Tiesong Lin","doi":"10.1016/j.msea.2025.149684","DOIUrl":"10.1016/j.msea.2025.149684","url":null,"abstract":"<div><div>DZ406 superalloy is a second-generation Ni-based precipitation strengthened directionally solidified superalloy, and shows great potential as a repair material for gas turbine blades. However, no research has been reported on the microstructure and mechanical properties of laser direct energy deposited (LDED) DZ406 superalloy. This study systematically investigates the as-deposited and heat-treated states of LDED DZ406, focusing on microstructure evolution, elemental segregation, and high-temperature tensile/rupture properties. The as-deposited layer exhibited a dendritic structure with inter-dendritic segregation and an absence of γ′ strengthening phase. Stress-rupture tests revealed that creep cracks nucleated at inter-dendritic elemental segregation zones and propagated along these weakened regions until fracture failure. The application of a novel short-term high-temperature aging treatment eliminated the inter-dendritic elemental segregation and enhanced the γ′ phase strengthening effect in the LDED DZ406 superalloy. The average grain diameter decreased from 163 μm to 66.4 μm, and the texture intensity decreased from 240 to 110. Under the combined effects of grain boundary strengthening and aging strengthening, the creep rupture strength of the heat-treated deposit increased from 300 MPa to 320 MPa, and the creep rupture life increased from 130.08 h to 155.44 h. Quantitative calculations indicate that grain boundary and aging strengthening contributed an increase in creep rupture strength of approximately 23.76 MPa, which is consistent with the creep rupture test results. These findings provide a theoretical foundation for turbine blade repair using DZ406 LDED technology.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"952 ","pages":"Article 149684"},"PeriodicalIF":7.0,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881547","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 : 2025-12-26DOI: 10.1016/j.msea.2025.149688
Xiaohan Guo, Yunfei Meng, Guanxiong Ding, Kang Guo, Hui Chen
Oscillating laser welding benefits weld formation and defect suppression for titanium alloy, yet often yields coarse prior β grains and brittle α′ martensite, leading to a poor strength-ductility balance. To address this, vanadium (V) and niobium (Nb) interlayers were separately introduced for in-situ microalloying during the welding. The results showed that the V addition improved weld appearance by reducing undercut for a smoother profile compared to unmodified weld. It also led to a 45 % reduction in surface height variation and lowered the porosity from 2.4 % to 0.8 %. Besides, a fine basket-weave α′ structure was promoted and the average grain size was refined to 1.09 μm. Along with an increase in β-phase content to 0.95 % and a rise in low-angle grain boundaries to 21.51 %, discontinuous β grain boundaries were formed, all of which contributed to weakened texture and anisotropy. The V-modified joint exhibited superior mechanical properties, with an elongation of 14.03 % (un-notched) and a notched ultimate tensile strength of 1278.52 MPa, marking a 20.5 % enhancement over the unmodified weld. These improvements are attributed to a strong β-stabilizing effect of V, which led to a lowered liquidus temperature, prolonged solidification time, promoted heterogeneous nucleation, and optimized phase transformation kinetics.
{"title":"Microstructure and property optimization of TC4 Titanium alloy welds through Nb/V alloying in oscillating laser welding","authors":"Xiaohan Guo, Yunfei Meng, Guanxiong Ding, Kang Guo, Hui Chen","doi":"10.1016/j.msea.2025.149688","DOIUrl":"10.1016/j.msea.2025.149688","url":null,"abstract":"<div><div>Oscillating laser welding benefits weld formation and defect suppression for titanium alloy, yet often yields coarse prior β grains and brittle α′ martensite, leading to a poor strength-ductility balance. To address this, vanadium (V) and niobium (Nb) interlayers were separately introduced for in-situ microalloying during the welding. The results showed that the V addition improved weld appearance by reducing undercut for a smoother profile compared to unmodified weld. It also led to a 45 % reduction in surface height variation and lowered the porosity from 2.4 % to 0.8 %. Besides, a fine basket-weave α′ structure was promoted and the average grain size was refined to 1.09 μm. Along with an increase in β-phase content to 0.95 % and a rise in low-angle grain boundaries to 21.51 %, discontinuous β grain boundaries were formed, all of which contributed to weakened texture and anisotropy. The V-modified joint exhibited superior mechanical properties, with an elongation of 14.03 % (un-notched) and a notched ultimate tensile strength of 1278.52 MPa, marking a 20.5 % enhancement over the unmodified weld. These improvements are attributed to a strong β-stabilizing effect of V, which led to a lowered liquidus temperature, prolonged solidification time, promoted heterogeneous nucleation, and optimized phase transformation kinetics.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"952 ","pages":"Article 149688"},"PeriodicalIF":7.0,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881544","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}
While work hardening mechanisms in metals have been studied mainly within the framework of dislocation theory, factors other than dislocations may affect work hardening behavior. When a polycrystalline metal deforms, individual grains tend to deform in different shapes due to plastic anisotropy. The gaps generated between grains are referred to as deformation incompatibility, which increases the work hardening rate. This hardening is generally attributed to the accumulation effect of geometrically necessary dislocations (GNDs). However, the elastic deformation to fill the gap explained by continuum mechanics also directly increases the stress. This study focused on the effect not of GND density but of elastic deformation induced by deformation incompatibility on work hardening, and tensile tests of commercially pure titanium (CP-Ti) with a basal split texture were conducted by experiments and crystal plasticity finite element (CPFE) analyses. The results showed that stress-strain curves changed depending on tensile direction, and the anisotropy was closely related to the difference in deformation incompatibility which varied depending on crystallographic orientations and active slip systems. A simple constitutive law was also proposed as a function of degree of deformation incompatibility, and could be used to quantify the effect of change in the deformation incompatibility due to the activation of slip systems on work hardening. These results indicate, for the first time, the possibility of controlling the work hardening rate of polycrystalline metals by the deformation incompatibility.
{"title":"Anisotropy in stress-strain relationship in commercially pure titanium enhanced by deformation incompatibility","authors":"Yoshiki Kawano , Masatoshi Mitsuhara , Tsuyoshi Mayama","doi":"10.1016/j.msea.2025.149690","DOIUrl":"10.1016/j.msea.2025.149690","url":null,"abstract":"<div><div>While work hardening mechanisms in metals have been studied mainly within the framework of dislocation theory, factors other than dislocations may affect work hardening behavior. When a polycrystalline metal deforms, individual grains tend to deform in different shapes due to plastic anisotropy. The gaps generated between grains are referred to as deformation incompatibility, which increases the work hardening rate. This hardening is generally attributed to the accumulation effect of geometrically necessary dislocations (GNDs). However, the elastic deformation to fill the gap explained by continuum mechanics also directly increases the stress. This study focused on the effect not of GND density but of elastic deformation induced by deformation incompatibility on work hardening, and tensile tests of commercially pure titanium (CP-Ti) with a basal split texture were conducted by experiments and crystal plasticity finite element (CPFE) analyses. The results showed that stress-strain curves changed depending on tensile direction, and the anisotropy was closely related to the difference in deformation incompatibility which varied depending on crystallographic orientations and active slip systems. A simple constitutive law was also proposed as a function of degree of deformation incompatibility, and could be used to quantify the effect of change in the deformation incompatibility due to the activation of slip systems on work hardening. These results indicate, for the first time, the possibility of controlling the work hardening rate of polycrystalline metals by the deformation incompatibility.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"952 ","pages":"Article 149690"},"PeriodicalIF":7.0,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881549","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 : 2025-12-26DOI: 10.1016/j.msea.2025.149662
Shenguang Liu, Mingyun Zhang, Lu Zhang, Rong Jiang, Liguo Zhao
Hydrogen-assisted fatigue crack growth was investigated for a powder metallurgy nickel-based superalloy FGH4096 under pre-charged hydrogen conditions. The dependence of fatigue crack growth rate on stress intensity and temperature was analyzed using advanced microscopy techniques, including scanning electron microscopy, electron backscatter diffraction, focused ion beam, and high-resolution transmission electron microscopy. The results revealed that hydrogen significantly increased fatigue crack growth rate, with greater acceleration observed at higher stress intensities. This phenomenon was attributed to hydrogen-facilitated planar slip and decohesion. Additionally, the hydrogen-accelerated fatigue crack growth was found to decrease with increasing temperature, becoming independent of stress intensity at 650 °C. This reduction was due to the diffusive loss of hydrogen at elevated temperatures and the diminishing of hydrogen-facilitated planar slip. Furthermore, the study explored the co-existing effects of hydrogen and oxygen on fatigue crack growth behaviour at high temperature, and the results demonstrated that the combined action of oxide layer fracture and hydrogen-enhanced planar decohesion accelerated the fatigue crack growth.
{"title":"Hydrogen-assisted fatigue crack growth in a nickel-based superalloy: Effects of stress intensity factor and temperature","authors":"Shenguang Liu, Mingyun Zhang, Lu Zhang, Rong Jiang, Liguo Zhao","doi":"10.1016/j.msea.2025.149662","DOIUrl":"10.1016/j.msea.2025.149662","url":null,"abstract":"<div><div>Hydrogen-assisted fatigue crack growth was investigated for a powder metallurgy nickel-based superalloy FGH4096 under pre-charged hydrogen conditions. The dependence of fatigue crack growth rate on stress intensity and temperature was analyzed using advanced microscopy techniques, including scanning electron microscopy, electron backscatter diffraction, focused ion beam, and high-resolution transmission electron microscopy. The results revealed that hydrogen significantly increased fatigue crack growth rate, with greater acceleration observed at higher stress intensities. This phenomenon was attributed to hydrogen-facilitated planar slip and decohesion. Additionally, the hydrogen-accelerated fatigue crack growth was found to decrease with increasing temperature, becoming independent of stress intensity at 650 °C. This reduction was due to the diffusive loss of hydrogen at elevated temperatures and the diminishing of hydrogen-facilitated planar slip. Furthermore, the study explored the co-existing effects of hydrogen and oxygen on fatigue crack growth behaviour at high temperature, and the results demonstrated that the combined action of oxide layer fracture and hydrogen-enhanced planar decohesion accelerated the fatigue crack growth.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"952 ","pages":"Article 149662"},"PeriodicalIF":7.0,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145838896","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 : 2025-12-26DOI: 10.1016/j.msea.2025.149676
Jiachen Jiang , Mushi Li , Yumin Wang , Lina Yang , Zhicong Gan , Jianan Hu , Qiuyue Jia , Rui Yang
The properties of SiCf/Ti composites are significantly influenced by the microstructure of the titanium alloy matrix. In this study, SiCf/Ti2AlNb composites were fabricated using a combination of magnetron sputtering and hot isostatic pressing (HIP). The effects of heat treatment, consisting of solution treatment and aging, on the microstructure and tensile properties of the SiCf/Ti2AlNb composites were investigated. The tensile properties of the composites were evaluated both before and after heat treatment through tensile tests conducted at room temperature and at 750 °C. Additionally, the reasons for the improvement in tensile strength at both room temperature and 750 °C were analyzed. The results show that, after 980 °C/2 h (AC) + 740 °C/24 h (AC), the α2 fraction in the SiCf/Ti2AlNb composite decreases, while acicular O precipitates form within the B2 phase. This improves deformation compatibility with the α2 phase during room-temperature tension, thereby increasing the room-temperature tensile strength by 221.4 MPa. The strength gain is attributed to the enhanced ability of the matrix to suppress crack initiation and hinder crack propagation. After 1080 °C/1 h (AC) + 980 °C/1 h (AC) + 740 °C/24 h (AC), the equiaxed α2 transforms into grain-boundary α2, accompanied by the precipitation of Ti3AlC particles and a higher density of acicular O within B2. The high-temperature tensile strength increases by 100.0 MPa, owing to the synergistic contribution of the α2, B2, and O phases; in particular, the Ti3AlC precipitates impart a particle-strengthening effect that enhances the high-temperature strength of the Ti2AlNb matrix. These findings suggest that different heat treatment regimes can be selected to regulate the microstructure of the composites, thereby enhancing their tensile strength at both room or high temperatures. This has significant implications for future engineering applications.
SiCf/Ti复合材料的性能受到钛合金基体微观组织的显著影响。本研究采用磁控溅射和热等静压相结合的方法制备了SiCf/Ti2AlNb复合材料。研究了固溶处理和时效处理对SiCf/Ti2AlNb复合材料显微组织和拉伸性能的影响。通过在室温和750℃下进行拉伸试验，评估了复合材料热处理前后的拉伸性能。此外，还分析了室温和750℃拉伸强度提高的原因。结果表明：经过980℃/2 h (AC) + 740℃/24 h （AC）后，SiCf/Ti2AlNb复合材料中α2组分减少，B2相内形成针状O析出；改善了室温拉伸过程中与α2相的变形相容性，室温拉伸强度提高221.4 MPa。强度的增加是由于基体抑制裂纹萌生和阻碍裂纹扩展的能力增强。经过1080°C/1 h (AC) + 980°C/1 h (AC) + 740°C/24 h （AC）后，等轴α2转变为晶界α2，并伴有Ti3AlC颗粒的析出和B2内针状O密度的增大。α2、B2和O相的协同作用使材料的高温抗拉强度提高了100.0 MPa；特别是，Ti3AlC析出物具有增强Ti2AlNb基体高温强度的颗粒强化效应。这些发现表明，可以选择不同的热处理方式来调节复合材料的微观结构，从而提高其在室温或高温下的抗拉强度。这对未来的工程应用具有重要意义。
{"title":"Influence of various heat treatment regimes on the microstructural and tensile properties of HIP-fabricated SiCf/Ti2AlNb composites","authors":"Jiachen Jiang , Mushi Li , Yumin Wang , Lina Yang , Zhicong Gan , Jianan Hu , Qiuyue Jia , Rui Yang","doi":"10.1016/j.msea.2025.149676","DOIUrl":"10.1016/j.msea.2025.149676","url":null,"abstract":"<div><div>The properties of SiC<sub>f</sub>/Ti composites are significantly influenced by the microstructure of the titanium alloy matrix. In this study, SiC<sub>f</sub>/Ti<sub>2</sub>AlNb composites were fabricated using a combination of magnetron sputtering and hot isostatic pressing (HIP). The effects of heat treatment, consisting of solution treatment and aging, on the microstructure and tensile properties of the SiC<sub>f</sub>/Ti<sub>2</sub>AlNb composites were investigated. The tensile properties of the composites were evaluated both before and after heat treatment through tensile tests conducted at room temperature and at 750 °C. Additionally, the reasons for the improvement in tensile strength at both room temperature and 750 °C were analyzed. The results show that, after 980 °C/2 h (AC) + 740 °C/24 h (AC), the α<sub>2</sub> fraction in the SiC<sub>f</sub>/Ti<sub>2</sub>AlNb composite decreases, while acicular O precipitates form within the B2 phase. This improves deformation compatibility with the α<sub>2</sub> phase during room-temperature tension, thereby increasing the room-temperature tensile strength by 221.4 MPa. The strength gain is attributed to the enhanced ability of the matrix to suppress crack initiation and hinder crack propagation. After 1080 °C/1 h (AC) + 980 °C/1 h (AC) + 740 °C/24 h (AC), the equiaxed α<sub>2</sub> transforms into grain-boundary α<sub>2</sub>, accompanied by the precipitation of Ti<sub>3</sub>AlC particles and a higher density of acicular O within B2. The high-temperature tensile strength increases by 100.0 MPa, owing to the synergistic contribution of the α<sub>2</sub>, B2, and O phases; in particular, the Ti<sub>3</sub>AlC precipitates impart a particle-strengthening effect that enhances the high-temperature strength of the Ti<sub>2</sub>AlNb matrix. These findings suggest that different heat treatment regimes can be selected to regulate the microstructure of the composites, thereby enhancing their tensile strength at both room or high temperatures. This has significant implications for future engineering applications.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149676"},"PeriodicalIF":7.0,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145847542","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 : 2025-12-26DOI: 10.1016/j.msea.2025.149687
F. Bahari-Sambran , F. Carreño , J. Medina , A. Orozco-Caballero , C.M. Cepeda-Jiménez
In this study, we investigate a new AlFeCrSi alloy designed for processing by gas atomization and laser powder bed fusion (LPBF). Optimization of processing parameters was carried out to achieve dense samples (∼99.8 %) and maximum hardness of ∼185 HV0.5. The mechanical properties at different temperatures up to 400 °C have been characterized by tensile and compression testing in the as-built condition. At room temperature, the new alloy achieves strength values comparable to Al2024-T3 and close to wrought Al7075-T6, while outperforming the LPBF commercial AlSi10Mg alloy and most newly reported LPBF Al alloys. Furthermore, it retains high mechanical strength up to 400 °C (UTS >150 MPa), surpassing both the same wrought alloys and recently developed LPBF Al alloys. The high strength is mainly associated to the addition of Si to the AlFeCr system, which induces the formation of a dense network of spherical and fine silicide phases (Al12(Fe,Cr)3)Si (∼20 nm)), instead of detrimental intermetallic Al13(Fe,Cr)2-4 phases. To ensure the only formation of silicides and considering the high cooling rate and the high Si solid solubility in the Al lattice, the alloy formulation requires for a higher Si content than the stoichiometrically necessary. Such extra Si content in solid solution influences the thermal stability and phase evolution at high temperatures. This study paves the way for designing suitable high strength aluminum alloys via LPBF and other additive manufacturing technologies.
{"title":"Microstructure, mechanical properties and thermal stability of a high-strength AlFeCrSi alloy processed by laser powder bed fusion","authors":"F. Bahari-Sambran , F. Carreño , J. Medina , A. Orozco-Caballero , C.M. Cepeda-Jiménez","doi":"10.1016/j.msea.2025.149687","DOIUrl":"10.1016/j.msea.2025.149687","url":null,"abstract":"<div><div>In this study, we investigate a new AlFeCrSi alloy designed for processing by gas atomization and laser powder bed fusion (LPBF). Optimization of processing parameters was carried out to achieve dense samples (∼99.8 %) and maximum hardness of ∼185 HV<sub>0.5</sub>. The mechanical properties at different temperatures up to 400 °C have been characterized by tensile and compression testing in the as-built condition. At room temperature, the new alloy achieves strength values comparable to Al2024-T3 and close to wrought Al7075-T6, while outperforming the LPBF commercial AlSi10Mg alloy and most newly reported LPBF Al alloys. Furthermore, it retains high mechanical strength up to 400 °C (UTS >150 MPa), surpassing both the same wrought alloys and recently developed LPBF Al alloys. The high strength is mainly associated to the addition of Si to the AlFeCr system, which induces the formation of a dense network of spherical and fine silicide phases (Al<sub>12</sub>(Fe,Cr)<sub>3</sub>)Si (∼20 nm)), instead of detrimental intermetallic Al<sub>13</sub>(Fe,Cr)<sub>2-4</sub> phases. To ensure the only formation of silicides and considering the high cooling rate and the high Si solid solubility in the Al lattice, the alloy formulation requires for a higher Si content than the stoichiometrically necessary. Such extra Si content in solid solution influences the thermal stability and phase evolution at high temperatures. This study paves the way for designing suitable high strength aluminum alloys via LPBF and other additive manufacturing technologies.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"952 ","pages":"Article 149687"},"PeriodicalIF":7.0,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881545","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 : 2025-12-25DOI: 10.1016/j.msea.2025.149672
Hongjie Zhang , Faquan Liu , Guorui Jiang , Xianglin Cui , Xiyun Yang , Wenyao Sun , Zubin Chen
This work proposes a novel approach of applying synchronous ultrasonic impact treatment during laser-directed energy deposition to induce columnar-to-equiaxed transition and twin formation throughout the deposited layer of an Al0.5CoCrFeNi high-entropy alloy. The microstructure and mechanical properties of the as-deposited alloy were investigated minutely, and providing an in-depth explanation of the grain refinement, twin formation, and strengthening mechanisms during deposition. The results demonstrate that ultrasonic impact treatment effectively transformed the coarse columnar grains into a refined equiaxed microstructure, achieving a remarkable grain refinement rate of 98 % and reducing the aspect ratio to nearly 1. Concurrently, the morphology of the BCC phase evolved from dendritic or acicular forms to a uniformly distributed lamellar structure. Furthermore, ultrasonic impact treatment significantly influenced the alloy's crystallographic texture, effectively eliminating the preferential orientation and thereby achieving structural isotropy. These microstructural improvements directly translated to superior mechanical properties. The ultrasonic impact treated samples retained a ductility of 25.6 % while exhibiting significant increases in yield strength and ultimate tensile strength by 82.7 MPa and 54.8 MPa, reaching 578.4 MPa and 903.4 MPa, respectively, attributing to the synergistic contributions of grain boundary strengthening and dislocation strengthening. This work presents a new strategy for fabricating HEAs via additive manufacturing that achieves a synergy between strength and ductility.
{"title":"Achieving strength-ductility synergy in laser deposited Al0.5CoCrFeNi high entropy alloy via grain refinement and twinning induced by synchronous ultrasonic impact","authors":"Hongjie Zhang , Faquan Liu , Guorui Jiang , Xianglin Cui , Xiyun Yang , Wenyao Sun , Zubin Chen","doi":"10.1016/j.msea.2025.149672","DOIUrl":"10.1016/j.msea.2025.149672","url":null,"abstract":"<div><div>This work proposes a novel approach of applying synchronous ultrasonic impact treatment during laser-directed energy deposition to induce columnar-to-equiaxed transition and twin formation throughout the deposited layer of an Al<sub>0.5</sub>CoCrFeNi high-entropy alloy. The microstructure and mechanical properties of the as-deposited alloy were investigated minutely, and providing an in-depth explanation of the grain refinement, twin formation, and strengthening mechanisms during deposition. The results demonstrate that ultrasonic impact treatment effectively transformed the coarse columnar grains into a refined equiaxed microstructure, achieving a remarkable grain refinement rate of 98 % and reducing the aspect ratio to nearly 1. Concurrently, the morphology of the BCC phase evolved from dendritic or acicular forms to a uniformly distributed lamellar structure. Furthermore, ultrasonic impact treatment significantly influenced the alloy's crystallographic texture, effectively eliminating the preferential orientation and thereby achieving structural isotropy. These microstructural improvements directly translated to superior mechanical properties. The ultrasonic impact treated samples retained a ductility of 25.6 % while exhibiting significant increases in yield strength and ultimate tensile strength by 82.7 MPa and 54.8 MPa, reaching 578.4 MPa and 903.4 MPa, respectively, attributing to the synergistic contributions of grain boundary strengthening and dislocation strengthening. This work presents a new strategy for fabricating HEAs via additive manufacturing that achieves a synergy between strength and ductility.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"952 ","pages":"Article 149672"},"PeriodicalIF":7.0,"publicationDate":"2025-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145838795","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 : 2025-12-24DOI: 10.1016/j.msea.2025.149680
Shuaibo Liu, Ji Gu, Min Song
In this study, annealing treatment was used to synergistically improve strength-ductility combination and strain-hardening capacity of a bi-layered Cu/Cu-6Al alloy. Prolonged annealing leads to the formation of unique serrated annealing twin boundaries, densely populated with stacking faults within the Cu-6Al layer. This is accompanied by a simultaneous increase in twin density and width of the interfacial transition zones (ITZs). The resulting microstructure enhances both hardness and strain hardening capacity. These improvements are attributed to three interrelated mechanisms: refinement of twin boundaries combined with interfacial stacking fault strengthening, hetero-deformation-induced (HDI) stress resulting from compositional gradients, and the activation of deformation twins. This work demonstrates that annealing is an effective strategy for optimizing laminated alloys through the engineered design of twin boundaries and heterogeneous interfaces.
{"title":"Annealing induced strength, ductility and strain-hardening synergy in a bi-layered Cu/Cu-6Al alloy","authors":"Shuaibo Liu, Ji Gu, Min Song","doi":"10.1016/j.msea.2025.149680","DOIUrl":"10.1016/j.msea.2025.149680","url":null,"abstract":"<div><div>In this study, annealing treatment was used to synergistically improve strength-ductility combination and strain-hardening capacity of a bi-layered Cu/Cu-6Al alloy. Prolonged annealing leads to the formation of unique serrated annealing twin boundaries, densely populated with stacking faults within the Cu-6Al layer. This is accompanied by a simultaneous increase in twin density and width of the interfacial transition zones (ITZs). The resulting microstructure enhances both hardness and strain hardening capacity. These improvements are attributed to three interrelated mechanisms: refinement of twin boundaries combined with interfacial stacking fault strengthening, hetero-deformation-induced (HDI) stress resulting from compositional gradients, and the activation of deformation twins. This work demonstrates that annealing is an effective strategy for optimizing laminated alloys through the engineered design of twin boundaries and heterogeneous interfaces.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"952 ","pages":"Article 149680"},"PeriodicalIF":7.0,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145838733","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}
Herein, a new high Co-Ni secondary hardening steel strengthened by co-precipitation of NiAl, Cu-rich precipitates (CRPs), and carbides was developed by optimizing the precipitation strategy. The evolution behavior of multiple precipitates and their effect on strength and ductility of new steel during aging at 460 °C were systematically investigated. The results reveal that the experimental steel exhibited unique mechanical properties at different aging stages, specifically, low stress brittle fracture at the initial stage of aging, superior combination of strength (2.5 GPa) and ductility (∼8.5 %) at the peak stage of aging, and high strength and low ductility at the over-aging stage. Three-dimensional atom probe results showed that the precipitation sequence of NiAl and CRPs in steel was as follows: supersaturated solid solution → isolated NiAl precepitates → NiAl/Cu co-precepitates, and the mechanism of NiAl on M2C was to induce nucleation and inhibit growth. Furthermore, the contribution of each strengthening factor was quantitatively assessed, and the high yield strength of peak-aging samples was attributed to precipitation strengthening (∼1121 MPa) and dislocation strengthening (∼995 MPa). Exceeding the peak aging, precipitation strengthening mechanism changes from the mixed mechanism of shearing and Orowan looping to one dominated by Orowan looping. This work constructs the correlation of “aging time-precipitate characteristics-fracture stress” based on the transition of yield strength and cleavage fracture stress, which provides a new insight for revealing the failure law of materials.
{"title":"Achieving strength-ductility synergy by tuning the configuration of nanoprecipitates in high Co-Ni secondary hardening steel","authors":"Jihang Li , Jialong Tian , Dongping Zhan , Zhouhua Jiang , Rustam Kaibyshev","doi":"10.1016/j.msea.2025.149666","DOIUrl":"10.1016/j.msea.2025.149666","url":null,"abstract":"<div><div>Herein, a new high Co-Ni secondary hardening steel strengthened by co-precipitation of NiAl, Cu-rich precipitates (CRPs), and carbides was developed by optimizing the precipitation strategy. The evolution behavior of multiple precipitates and their effect on strength and ductility of new steel during aging at 460 °C were systematically investigated. The results reveal that the experimental steel exhibited unique mechanical properties at different aging stages, specifically, low stress brittle fracture at the initial stage of aging, superior combination of strength (2.5 GPa) and ductility (∼8.5 %) at the peak stage of aging, and high strength and low ductility at the over-aging stage. Three-dimensional atom probe results showed that the precipitation sequence of NiAl and CRPs in steel was as follows: supersaturated solid solution → isolated NiAl precepitates → NiAl/Cu co-precepitates, and the mechanism of NiAl on M<sub>2</sub>C was to induce nucleation and inhibit growth. Furthermore, the contribution of each strengthening factor was quantitatively assessed, and the high yield strength of peak-aging samples was attributed to precipitation strengthening (∼1121 MPa) and dislocation strengthening (∼995 MPa). Exceeding the peak aging, precipitation strengthening mechanism changes from the mixed mechanism of shearing and Orowan looping to one dominated by Orowan looping. This work constructs the correlation of “aging time-precipitate characteristics-fracture stress” based on the transition of yield strength and cleavage fracture stress, which provides a new insight for revealing the failure law of materials.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"952 ","pages":"Article 149666"},"PeriodicalIF":7.0,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145838802","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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