Pub Date : 2026-01-16DOI: 10.1016/j.msea.2026.149802
Honghong Su , Yixi Hou , Jiatao Ye , Chen Sun , Cheng Jiang , Yaxi Ma , Xiaoran Zhao , Luyan Yang , Xiao Wei , Shengcheng Mao , Xiaodong Han
Precipitation strengthening via coherent L12 nanoprecipitates has emerged as an ideal strategy for designing high-performance materials. Most traditional design methods make it difficult to introduce a pure L12 structure into CoCrNi alloys by adding Al elements, which usually leads to a loss of ductility. This study designed an Al0.3CoCr0.9Ni2.5 multi-principal element alloys through strategic Ni and Al compositional optimization, obtaining a high-density L12 nanoprecipitate structure that exhibits an exceptional combination of high strength and remarkable ductility. The preserved ductility stems from the synergistic interactions between stacking fault networks with Lomer-Cottrell (L-C) locks and deformation twinning. These mechanisms collectively induce a dynamic Hall-Petch effect and shorten the dislocation mean free path, thus enabling the high strain hardening capability. This innovative compositional design strategy demonstrates a viable pathway for designing high-performance precipitation-strengthened alloys.
{"title":"Tailoring Ni/Al content drives L12 precipitation achieving synergistic improvement of strength and ductility","authors":"Honghong Su , Yixi Hou , Jiatao Ye , Chen Sun , Cheng Jiang , Yaxi Ma , Xiaoran Zhao , Luyan Yang , Xiao Wei , Shengcheng Mao , Xiaodong Han","doi":"10.1016/j.msea.2026.149802","DOIUrl":"10.1016/j.msea.2026.149802","url":null,"abstract":"<div><div>Precipitation strengthening via coherent L1<sub>2</sub> nanoprecipitates has emerged as an ideal strategy for designing high-performance materials. Most traditional design methods make it difficult to introduce a pure L1<sub>2</sub> structure into CoCrNi alloys by adding Al elements, which usually leads to a loss of ductility. This study designed an Al<sub>0.3</sub>CoCr<sub>0.9</sub>Ni<sub>2.5</sub> multi-principal element alloys through strategic Ni and Al compositional optimization, obtaining a high-density L1<sub>2</sub> nanoprecipitate structure that exhibits an exceptional combination of high strength and remarkable ductility. The preserved ductility stems from the synergistic interactions between stacking fault networks with Lomer-Cottrell (L-C) locks and deformation twinning. These mechanisms collectively induce a dynamic Hall-Petch effect and shorten the dislocation mean free path, thus enabling the high strain hardening capability. This innovative compositional design strategy demonstrates a viable pathway for designing high-performance precipitation-strengthened alloys.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149802"},"PeriodicalIF":7.0,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023444","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 : 2026-01-16DOI: 10.1016/j.msea.2026.149801
Ramamoorthy Velayutham, Sudhir Behera, S. Sridharan, Jayaprakash Murugesan
Solid-state additive manufacturing is gaining attention for fabricating lightweight alloys with enhanced mechanical properties due to its low thermal input. In this work, a multilayer AA7075 (Al-Zn-Mg-Cu) alloy structure was developed using Friction Stir Powder Additive Manufacturing (FSPAM). A detailed study was then conducted to evaluate the influence of post-deposition heat treatments (T6 and T73) on the resulting microstructure, microhardness, and tensile behaviour of the as-deposited (AD) samples. The AD condition exhibited fine, equiaxed grains resulting from continuous dynamic recrystallization (CDRX). While the heat treatments had little effect on grain size, they significantly altered the nature and distribution of precipitates. After T6 treatment, fine η′ precipitates were observed within grains, along with coarser η precipitates at grain boundaries. The T6-treated sample achieved the highest ultimate tensile strength (UTS) of 560 MPa, with reduced ductility compared to both the AD and T73-treated specimens. Following the T73 heat treatment, the η′ precipitates underwent coarsening into the more stable η phase, which resulted in a reduction in UTS while enhancing ductility, as evidenced by the highest observed elongation among the tested conditions. Fractographic analysis of the as-deposited (AD) tensile specimens revealed features indicative of partial ductile fracture. In contrast, the T6-treated samples exhibited a reduced number of dimples containing fine precipitate particles, suggesting a more brittle fracture behaviour. The T73 specimens, however, displayed a higher density of larger dimples with coarser precipitates, consistent with the improved ductility resulting from the overaged microstructure. These findings demonstrate that the mechanical performance of FSPAM-processed aluminium alloys can be effectively tailored through the selection of appropriate post-heat treatment (T6 or T73), depending on the targeted application requirements.
{"title":"Effect of heat treatments on microstructure and strengthening mechanisms of friction stir powder additive-manufactured Al-Zn-Mg-Cu aluminium alloy","authors":"Ramamoorthy Velayutham, Sudhir Behera, S. Sridharan, Jayaprakash Murugesan","doi":"10.1016/j.msea.2026.149801","DOIUrl":"10.1016/j.msea.2026.149801","url":null,"abstract":"<div><div>Solid-state additive manufacturing is gaining attention for fabricating lightweight alloys with enhanced mechanical properties due to its low thermal input. In this work, a multilayer AA7075 (Al-Zn-Mg-Cu) alloy structure was developed using Friction Stir Powder Additive Manufacturing (FSPAM). A detailed study was then conducted to evaluate the influence of post-deposition heat treatments (T6 and T73) on the resulting microstructure, microhardness, and tensile behaviour of the as-deposited (AD) samples. The AD condition exhibited fine, equiaxed grains resulting from continuous dynamic recrystallization (CDRX). While the heat treatments had little effect on grain size, they significantly altered the nature and distribution of precipitates. After T6 treatment, fine η′ precipitates were observed within grains, along with coarser η precipitates at grain boundaries. The T6-treated sample achieved the highest ultimate tensile strength (UTS) of 560 MPa, with reduced ductility compared to both the AD and T73-treated specimens. Following the T73 heat treatment, the η′ precipitates underwent coarsening into the more stable η phase, which resulted in a reduction in UTS while enhancing ductility, as evidenced by the highest observed elongation among the tested conditions. Fractographic analysis of the as-deposited (AD) tensile specimens revealed features indicative of partial ductile fracture. In contrast, the T6-treated samples exhibited a reduced number of dimples containing fine precipitate particles, suggesting a more brittle fracture behaviour. The T73 specimens, however, displayed a higher density of larger dimples with coarser precipitates, consistent with the improved ductility resulting from the overaged microstructure. These findings demonstrate that the mechanical performance of FSPAM-processed aluminium alloys can be effectively tailored through the selection of appropriate post-heat treatment (T6 or T73), depending on the targeted application requirements.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149801"},"PeriodicalIF":7.0,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023405","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 : 2026-01-16DOI: 10.1016/j.msea.2026.149785
K.G. Jayaram , J. Quibel , J. Huret , A. Descamps-Mandine , O. Smerdova , W.-J. Chitty , G. Henaff
Components in the primary loop of a nuclear reactor are subjected to thermal aging during long-term operation in Pressurized Water Reactors (PWRs). Among the materials used in reactor components, Alloy 690 TT, a nickel-based alloy, is used in some critical components of the reactor. Despite existing studies on Alloy 690, further investigation is needed to fully understand the effects of prolonged thermal aging on its microstructure and mechanical properties. This study evaluates the impact of thermal aging on the microstructural evolution and mechanical properties of an Alloy 690 TT. An as-received sample was subjected to accelerated aging at 420 °C, with periodic microstructural analyses focusing on intergranular and intragranular precipitate characteristics, including area, density, width, and length fraction. The evolution of the mechanical properties of the alloy was assessed through microhardness and nanoindentation tests to evaluate both global and local variations. Finally, by coupling nano-hardness and transmission electron microscopy, the formation of short-range ordering was investigated. The results indicate a slight increase in the intergranular precipitate area after 5300 h of aging (equivalent to 80 years of operation), along with an increase in the density of intragranular precipitates. Moreover, a direct link was made between the formation of Short-Range Ordering and the increase in nanohardness, particularly near the grain boundaries. These findings establish a direct link between microstructural changes and mechanical properties in aged Alloy 690 TT, providing insights into its long-term performance in nuclear reactors.
{"title":"Effect of thermal aging at 420 °C on the microstructure of alloy 690 TT","authors":"K.G. Jayaram , J. Quibel , J. Huret , A. Descamps-Mandine , O. Smerdova , W.-J. Chitty , G. Henaff","doi":"10.1016/j.msea.2026.149785","DOIUrl":"10.1016/j.msea.2026.149785","url":null,"abstract":"<div><div>Components in the primary loop of a nuclear reactor are subjected to thermal aging during long-term operation in Pressurized Water Reactors (PWRs). Among the materials used in reactor components, Alloy 690 TT, a nickel-based alloy, is used in some critical components of the reactor. Despite existing studies on Alloy 690, further investigation is needed to fully understand the effects of prolonged thermal aging on its microstructure and mechanical properties. This study evaluates the impact of thermal aging on the microstructural evolution and mechanical properties of an Alloy 690 TT. An as-received sample was subjected to accelerated aging at 420 °C, with periodic microstructural analyses focusing on intergranular and intragranular precipitate characteristics, including area, density, width, and length fraction. The evolution of the mechanical properties of the alloy was assessed through microhardness and nanoindentation tests to evaluate both global and local variations. Finally, by coupling nano-hardness and transmission electron microscopy, the formation of short-range ordering was investigated. The results indicate a slight increase in the intergranular precipitate area after 5300 h of aging (equivalent to 80 years of operation), along with an increase in the density of intragranular precipitates. Moreover, a direct link was made between the formation of Short-Range Ordering and the increase in nanohardness, particularly near the grain boundaries. These findings establish a direct link between microstructural changes and mechanical properties in aged Alloy 690 TT, providing insights into its long-term performance in nuclear reactors.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149785"},"PeriodicalIF":7.0,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023404","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 : 2026-01-16DOI: 10.1016/j.msea.2026.149794
Zhi Chen , Lei Zhang , Zouhao Song , Xiaoyan Wu , Guojun Zhang , Fenglin Han
Due to the extreme service environments, wear and fatigue failure are prone to occur during the service of aerospace superalloy. Excellent anti-fatigue and wear-resistant surfaces usually require high surface mechanical properties and low surface roughness. Ultrasonic shot peening is a commonly used surface strengthening method for aerospace superalloy. However, the traditional ultrasonic shot peening process for aerospace superalloy faces an insurmountable challenge: it is difficult to simultaneously obtain surfaces with low surface roughness and high surface mechanical properties. In addition, the residual compressive stress induced by ultrasonic shot peening is prone to stress relaxation in high-temperature environments. In response to this issue, this study proposes a new method of surface strengthening for aerospace superalloy based on cryogenic pretreatment and ultrasonic peening. By comparing with the ordinary ultrasonic shot peening, the effect of cryogenic pretreatment and ultrasonic shot peening on the surface morphology, microstructure and surface mechanical properties of aerospace superalloy is systematically explored. The process parameters are as follows: ultrasonic power of 1000 W–2000W, peening time of 5min–15min, cryogenic pretreatment temperature of −196 °C, cryogenic pretreatment time of 3 h–6h, shot material of S110 cast steel. The experimental results indicate that: compared with single ultrasonic shot peening, the cryogenic pretreatment and ultrasonic shot peening can effectively reduce the surface roughness, promote grain refinement and the precipitation of strengthening phases, increase surface hardness (maximum value of 620 HV) and residual compressive stress (maximum value of −789 MPa), and reduce the high-temperature relaxation amplitude of residual stress. Under the same surface roughness, the cryogenic pretreatment can increase residual compressive stress by 36.2 % (from −530 MPa to −722 MPa). Under the same residual compressive stress on the surface, cryogenic pretreatment can reduce surface roughness by 45.1 % (from 1.62 μm to 0.89 μm). In addition, the cryogenic pretreatment and ultrasonic shot peening can reduce residual compressive stress relaxation amplitude by 8–35.9 %. Therefore, the cryogenic pretreatment and ultrasonic shot peening proposed in this study has good application potential and promotion value for the practical engineering.
{"title":"A new method of surface strengthening for GH4169 superalloy based on cryogenic pretreatment and ultrasonic shot peening","authors":"Zhi Chen , Lei Zhang , Zouhao Song , Xiaoyan Wu , Guojun Zhang , Fenglin Han","doi":"10.1016/j.msea.2026.149794","DOIUrl":"10.1016/j.msea.2026.149794","url":null,"abstract":"<div><div>Due to the extreme service environments, wear and fatigue failure are prone to occur during the service of aerospace superalloy. Excellent anti-fatigue and wear-resistant surfaces usually require high surface mechanical properties and low surface roughness. Ultrasonic shot peening is a commonly used surface strengthening method for aerospace superalloy. However, the traditional ultrasonic shot peening process for aerospace superalloy faces an insurmountable challenge: it is difficult to simultaneously obtain surfaces with low surface roughness and high surface mechanical properties. In addition, the residual compressive stress induced by ultrasonic shot peening is prone to stress relaxation in high-temperature environments. In response to this issue, this study proposes a new method of surface strengthening for aerospace superalloy based on cryogenic pretreatment and ultrasonic peening. By comparing with the ordinary ultrasonic shot peening, the effect of cryogenic pretreatment and ultrasonic shot peening on the surface morphology, microstructure and surface mechanical properties of aerospace superalloy is systematically explored. The process parameters are as follows: ultrasonic power of 1000 W–2000W, peening time of 5min–15min, cryogenic pretreatment temperature of −196 °C, cryogenic pretreatment time of 3 h–6h, shot material of S110 cast steel. The experimental results indicate that: compared with single ultrasonic shot peening, the cryogenic pretreatment and ultrasonic shot peening can effectively reduce the surface roughness, promote grain refinement and the precipitation of strengthening phases, increase surface hardness (maximum value of 620 HV) and residual compressive stress (maximum value of −789 MPa), and reduce the high-temperature relaxation amplitude of residual stress. Under the same surface roughness, the cryogenic pretreatment can increase residual compressive stress by 36.2 % (from −530 MPa to −722 MPa). Under the same residual compressive stress on the surface, cryogenic pretreatment can reduce surface roughness by 45.1 % (from 1.62 μm to 0.89 μm). In addition, the cryogenic pretreatment and ultrasonic shot peening can reduce residual compressive stress relaxation amplitude by 8–35.9 %. Therefore, the cryogenic pretreatment and ultrasonic shot peening proposed in this study has good application potential and promotion value for the practical engineering.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149794"},"PeriodicalIF":7.0,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023447","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 : 2026-01-16DOI: 10.1016/j.msea.2026.149791
Zhongliang Shu , Jianling Liu , Tao Zhou , Peng Dong , Changli Ma , Taisen Zuo , Changshu Xiang , Yu Guo , Chao Chen , Kechao Zhou
This study addresses the long-standing controversy regarding precipitation behavior and their quantitative impact on strengthening and conductive mechanism in Cu-Cr-Nb alloys fabricated by laser powder bed fusion (LPBF). Small-angle neutron scattering (SANS) with a spherical model and polydispersity analysis was utilized to statistically assess the size distribution and volume fraction of the nanoprecipitates within the centimeter-scale bulk. The structure of these multimodal precipitates and their interface characteristics were further elucidated by high-resolution transmission electron microscope (HRTEM), corroborating the SANS data interpretation. It was demonstrated that the as-built Cu-Cr-Nb features bimodal grains with dual-scale C15-Cr2Nb and C14-Cr2Nb nanoprecipitates. Specifically, the C15 forms incoherent interfaces, while the C14 exhibits an orientation relationship with the matrix. Aging at 450 °C induces a trimodal distribution (∼1 nm, ∼5 nm, >10 nm) with coherent Cr-rich particles at the finest scale, achieving a peak tensile strength of 924 MPa. Elevated aging leads to a coarser-trimodal distribution comprising C15-Cr2Nb, C14-Cr2Nb, and BCC-Cr, ultimately achieving an excellent combination of 448 MPa yield strength and 73 % IACS conductivity. This work presents a viable way for tailoring the nanoprecipitates in additively-manufactured Cu-Cr-Nb alloys to overcome the strength-conductivity trade-off, and providing design insights for next-generation thermal management materials.
{"title":"Size evolution of multimodal nanoprecipitates and synergistic strength-conductivity mechanisms in LPBF-processed Cu-Cr-Nb alloys","authors":"Zhongliang Shu , Jianling Liu , Tao Zhou , Peng Dong , Changli Ma , Taisen Zuo , Changshu Xiang , Yu Guo , Chao Chen , Kechao Zhou","doi":"10.1016/j.msea.2026.149791","DOIUrl":"10.1016/j.msea.2026.149791","url":null,"abstract":"<div><div>This study addresses the long-standing controversy regarding precipitation behavior and their quantitative impact on strengthening and conductive mechanism in Cu-Cr-Nb alloys fabricated by laser powder bed fusion (LPBF). Small-angle neutron scattering (SANS) with a spherical model and polydispersity analysis was utilized to statistically assess the size distribution and volume fraction of the nanoprecipitates within the centimeter-scale bulk. The structure of these multimodal precipitates and their interface characteristics were further elucidated by high-resolution transmission electron microscope (HRTEM), corroborating the SANS data interpretation. It was demonstrated that the as-built Cu-Cr-Nb features bimodal grains with dual-scale C15-Cr<sub>2</sub>Nb and C14-Cr<sub>2</sub>Nb nanoprecipitates. Specifically, the C15 forms incoherent interfaces, while the C14 exhibits an orientation relationship with the matrix. Aging at 450 °C induces a trimodal distribution (∼1 nm, ∼5 nm, >10 nm) with coherent Cr-rich particles at the finest scale, achieving a peak tensile strength of 924 MPa. Elevated aging leads to a coarser-trimodal distribution comprising C15-Cr<sub>2</sub>Nb, C14-Cr<sub>2</sub>Nb, and BCC-Cr, ultimately achieving an excellent combination of 448 MPa yield strength and 73 % IACS conductivity. This work presents a viable way for tailoring the nanoprecipitates in additively-manufactured Cu-Cr-Nb alloys to overcome the strength-conductivity trade-off, and providing design insights for next-generation thermal management materials.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149791"},"PeriodicalIF":7.0,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023445","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 : 2026-01-15DOI: 10.1016/j.msea.2026.149799
Ming Chen , Feng Hu , Songbo Zhou , Serhii Yershov , Kaiming Wu
The mechanism of the synergistic effect of microstructural evolution on fracture toughness in low-density δ-ferrite steel under varying rolling temperatures was systematically investigated in this study. The findings indicated that a lamellar microstructure can be formed through high-temperature rolling (850–950 °C), consisting of δ-ferrite, honeycomb martensite lamellae, and equiaxed ferrite grains which are formed by DIFT (deformation-induced ferrite phase transformation) within the honeycomb structure. Together with the concentration of interfacial stress, the equiaxed DIF (deformation induced ferrite) grains served as pre-existing defects, resulting in an impact energy of less than 7 J at room temperature (elongation less than 9 %). Meanwhile, the monotonically decreasing θ-curve indicated that deformation coordination was hampered by phase hardness mismatch (martensite/ferrite hardness difference >3.3 GPa). Conversely, a lamellar microstructure with alternating δ-ferrite lamellae and composite lamellae of ultra-fine spherical carbides (diameter <250 nm)/ferrite was formed by low-temperature rolling (650–750 °C). Under the influence of the Orowan mechanism, cracks hardly propagated through the lamellae containing ultra-fine spherical carbides, which forced cracks to deflect horizontally and extended the propagation path. At the same time, the presence of these carbides increased the curvature radius of the crack tip to reduce stress concentration, and the microvoids induced by carbides also promoted horizontal crack propagation along lamellar boundaries. These multiple mechanisms collectively enhanced material toughness, resulting in an impact absorption energy of up to 207.5 J (elongation 19.8 %). These results suggested a new pathway for the strength-toughness regulation of lightweight steel.
{"title":"Enabling superior impact toughness of low-density δ-ferrite steel by dispersing ultra-fine spheroidized carbides in the ferrite/carbide composite lamellae","authors":"Ming Chen , Feng Hu , Songbo Zhou , Serhii Yershov , Kaiming Wu","doi":"10.1016/j.msea.2026.149799","DOIUrl":"10.1016/j.msea.2026.149799","url":null,"abstract":"<div><div>The mechanism of the synergistic effect of microstructural evolution on fracture toughness in low-density δ-ferrite steel under varying rolling temperatures was systematically investigated in this study. The findings indicated that a lamellar microstructure can be formed through high-temperature rolling (850–950 °C), consisting of δ-ferrite, honeycomb martensite lamellae, and equiaxed ferrite grains which are formed by DIFT (deformation-induced ferrite phase transformation) within the honeycomb structure. Together with the concentration of interfacial stress, the equiaxed DIF (deformation induced ferrite) grains served as pre-existing defects, resulting in an impact energy of less than 7 J at room temperature (elongation less than 9 %). Meanwhile, the monotonically decreasing θ-curve indicated that deformation coordination was hampered by phase hardness mismatch (martensite/ferrite hardness difference >3.3 GPa). Conversely, a lamellar microstructure with alternating δ-ferrite lamellae and composite lamellae of ultra-fine spherical carbides (diameter <250 nm)/ferrite was formed by low-temperature rolling (650–750 °C). Under the influence of the Orowan mechanism, cracks hardly propagated through the lamellae containing ultra-fine spherical carbides, which forced cracks to deflect horizontally and extended the propagation path. At the same time, the presence of these carbides increased the curvature radius of the crack tip to reduce stress concentration, and the microvoids induced by carbides also promoted horizontal crack propagation along lamellar boundaries. These multiple mechanisms collectively enhanced material toughness, resulting in an impact absorption energy of up to 207.5 J (elongation 19.8 %). These results suggested a new pathway for the strength-toughness regulation of lightweight steel.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149799"},"PeriodicalIF":7.0,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973538","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 : 2026-01-15DOI: 10.1016/j.msea.2026.149792
Qingfeng Kang , Zexi Zhang , Hui Wang , Haifeng Xu , Cunyu Wang , Zhengdong Liu , Wenquan Cao
The microstructure and mechanical properties of Fe-35Mn-xAl-0.1C (x = 4, 6, 8, 10) low-density steels were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile machine. It is found that the microstructure evolves with the increasing of Al content from a single austenite phase steel for 4 %Al, to a ferrite-based duplex steel for 8 %Al, but nearly a fully ferrite phase steel with 10 %Al. As the Al content is increased from 4 wt % to 8 wt %, the yield strength and tensile strength are significantly increased from 239 MPa to 552 MPa–455 MPa and 740 MPa, respectively, while the uniform elongation is only slightly decreased from 38.5 % to 31.0 %. However, as the Al content is increased up to 10 %, the yield strength is gradually increased to 585 MPa, but the tensile elongation is sharply decreased down to about 4.6 %. Based on the thorough microstructure examination of the dislocation type and dislocation pattern and the microstructure evolution during tensile deformation, it is concluded that the excellent combination of the mechanical property of the 8Al steel is realized by the activation of the edge-typed dislocation and dynamic slip band refinement in the ferrite grain mitigated by the surrounded austenite grains, which enhanced the strain hardening rate significantly. This study not only reveals a new ductility-enhancing mechanism of ferrite + austenite duplex steel, but also provides a new route for designing BCC based low-density steel with high strength and high ductility.
{"title":"Duplex microstructure enhanced mechanical property and underlined mechanism in Fe35MnxAl0.1C low-density steel","authors":"Qingfeng Kang , Zexi Zhang , Hui Wang , Haifeng Xu , Cunyu Wang , Zhengdong Liu , Wenquan Cao","doi":"10.1016/j.msea.2026.149792","DOIUrl":"10.1016/j.msea.2026.149792","url":null,"abstract":"<div><div>The microstructure and mechanical properties of Fe-35Mn-xAl-0.1C (x = 4, 6, 8, 10) low-density steels were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile machine. It is found that the microstructure evolves with the increasing of Al content from a single austenite phase steel for 4 %Al, to a ferrite-based duplex steel for 8 %Al, but nearly a fully ferrite phase steel with 10 %Al. As the Al content is increased from 4 wt % to 8 wt %, the yield strength and tensile strength are significantly increased from 239 MPa to 552 MPa–455 MPa and 740 MPa, respectively, while the uniform elongation is only slightly decreased from 38.5 % to 31.0 %. However, as the Al content is increased up to 10 %, the yield strength is gradually increased to 585 MPa, but the tensile elongation is sharply decreased down to about 4.6 %. Based on the thorough microstructure examination of the dislocation type and dislocation pattern and the microstructure evolution during tensile deformation, it is concluded that the excellent combination of the mechanical property of the 8Al steel is realized by the activation of the edge-typed dislocation and dynamic slip band refinement in the ferrite grain mitigated by the surrounded austenite grains, which enhanced the strain hardening rate significantly. This study not only reveals a new ductility-enhancing mechanism of ferrite + austenite duplex steel, but also provides a new route for designing BCC based low-density steel with high strength and high ductility.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149792"},"PeriodicalIF":7.0,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973664","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 : 2026-01-15DOI: 10.1016/j.msea.2026.149797
Linxiang Liu, Qingfeng Wu, Zhijun Wang, Junjie Li, Jincheng Wang
FCC/B2 dual-phase high-entropy alloys (DHEAs) exhibit great potential for high-temperature applications due to their unique combination of low density, excellent mechanical properties, and good oxidation resistance. However, achieving an optimal strength-ductility balance at elevated temperatures remains a challenge. In this study, the dual-phase and precipitation structures of FCC/B2 DHEAs were systematically tailored by varying the Ni/Co content. It was found that an increased Ni/Co ratio resulted in a lower fraction of the B2 phase and promoted L12 precipitation within both the FCC and B2 phases. The optimized microstructure was featured by a balanced combination of dual-phase matrix and high-density precipitates. At 800 °C, the increased volume fraction of L12 precipitates improved the yield strength, while the retained B2 phase effectively suppressed intergranular cracking, thereby preserving ductility. These findings offer a practical strategy for designing low-density, high-performance FCC/B2 DHEAs for future high-temperature structural applications.
{"title":"Engineering L12 precipitate and intergranular B2 phase for simultaneous high-temperature strength and fracture resistance in FCC/B2 high-entropy alloys","authors":"Linxiang Liu, Qingfeng Wu, Zhijun Wang, Junjie Li, Jincheng Wang","doi":"10.1016/j.msea.2026.149797","DOIUrl":"10.1016/j.msea.2026.149797","url":null,"abstract":"<div><div>FCC/B2 dual-phase high-entropy alloys (DHEAs) exhibit great potential for high-temperature applications due to their unique combination of low density, excellent mechanical properties, and good oxidation resistance. However, achieving an optimal strength-ductility balance at elevated temperatures remains a challenge. In this study, the dual-phase and precipitation structures of FCC/B2 DHEAs were systematically tailored by varying the Ni/Co content. It was found that an increased Ni/Co ratio resulted in a lower fraction of the B2 phase and promoted L1<sub>2</sub> precipitation within both the FCC and B2 phases. The optimized microstructure was featured by a balanced combination of dual-phase matrix and high-density precipitates. At 800 °C, the increased volume fraction of L1<sub>2</sub> precipitates improved the yield strength, while the retained B2 phase effectively suppressed intergranular cracking, thereby preserving ductility. These findings offer a practical strategy for designing low-density, high-performance FCC/B2 DHEAs for future high-temperature structural applications.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149797"},"PeriodicalIF":7.0,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023446","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 : 2026-01-14DOI: 10.1016/j.msea.2026.149788
Xuezhao Wang , Ping Zhang , Xiaomin Jiang , Youqiang Wang
The dynamic deformation behavior and underlying mechanisms of a peak-aged extruded Mg–7.5Gd–3Y–0.5Zr alloy were systematically investigated under combined high-temperature and high–strain-rate conditions. Dynamic compression tests were conducted using a Split Hopkinson Pressure Bar (SHPB) system equipped with a high-temperature device over a wide range of strain rates. Post-impact microstructural evolution was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD) to establish correlations between mechanical response and temperature-dependent deformation mechanisms.The results demonstrate that the alloy exhibits excellent impact resistance and thermal stability at elevated temperatures, achieving compressive strengths of approximately 664 MPa at 100 °C, 638 MPa at 200 °C, and 619 MPa at 300 °C. At low strain rates, the strengthening behavior is governed by the combined effects of rare-earth hydride particles, age-hardening precipitates, and dynamically formed precipitates, with their relative contributions evolving as temperature increases. In contrast, under high strain rate loading, increasing temperature suppresses dynamic precipitation while promoting twinning, dynamic recrystallization, and adiabatic shear localization. In this regime, thermally stable age-hardening precipitates play a dominant role in maintaining impact strength.The active deformation mechanisms exhibit a clear temperature-dependent transition at high strain rates. Pyramidal slip dominates at 100 °C, while secondary compressive and tensile twinning becomes predominant at 200 °C, accompanied by cooperative activation of multiple slip systems. At 300 °C, basal slip and tensile twinning govern plastic deformation, with pyramidal slip assisting strain accommodation. These transitions reflect enhanced thermal activation of slip and twinning mechanisms at elevated temperatures.Overall, the Mg–7.5Gd–3Y–0.5Zr alloy demonstrates excellent adaptability and stable dynamic mechanical performance under extreme conditions. The synergistic effects of rare-earth strengthening, precipitation behavior, and temperature-dependent deformation mechanisms highlight its strong potential for high-temperature, high–strain-rate lightweight structural applications.
{"title":"Study on the high-temperature dynamic impact mechanical behavior and deformation mechanisms of extruded Mg-Gd alloys","authors":"Xuezhao Wang , Ping Zhang , Xiaomin Jiang , Youqiang Wang","doi":"10.1016/j.msea.2026.149788","DOIUrl":"10.1016/j.msea.2026.149788","url":null,"abstract":"<div><div>The dynamic deformation behavior and underlying mechanisms of a peak-aged extruded Mg–7.5Gd–3Y–0.5Zr alloy were systematically investigated under combined high-temperature and high–strain-rate conditions. Dynamic compression tests were conducted using a Split Hopkinson Pressure Bar (SHPB) system equipped with a high-temperature device over a wide range of strain rates. Post-impact microstructural evolution was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD) to establish correlations between mechanical response and temperature-dependent deformation mechanisms.The results demonstrate that the alloy exhibits excellent impact resistance and thermal stability at elevated temperatures, achieving compressive strengths of approximately 664 MPa at 100 °C, 638 MPa at 200 °C, and 619 MPa at 300 °C. At low strain rates, the strengthening behavior is governed by the combined effects of rare-earth hydride particles, age-hardening precipitates, and dynamically formed precipitates, with their relative contributions evolving as temperature increases. In contrast, under high strain rate loading, increasing temperature suppresses dynamic precipitation while promoting twinning, dynamic recrystallization, and adiabatic shear localization. In this regime, thermally stable age-hardening precipitates play a dominant role in maintaining impact strength.The active deformation mechanisms exhibit a clear temperature-dependent transition at high strain rates. Pyramidal slip dominates at 100 °C, while secondary compressive and tensile twinning becomes predominant at 200 °C, accompanied by cooperative activation of multiple slip systems. At 300 °C, basal slip and tensile twinning govern plastic deformation, with pyramidal slip assisting strain accommodation. These transitions reflect enhanced thermal activation of slip and twinning mechanisms at elevated temperatures.Overall, the Mg–7.5Gd–3Y–0.5Zr alloy demonstrates excellent adaptability and stable dynamic mechanical performance under extreme conditions. The synergistic effects of rare-earth strengthening, precipitation behavior, and temperature-dependent deformation mechanisms highlight its strong potential for high-temperature, high–strain-rate lightweight structural applications.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149788"},"PeriodicalIF":7.0,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973655","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 : 2026-01-14DOI: 10.1016/j.msea.2026.149775
Xin Bu , Qian Lei , Xiukuang Zhang , Cong Chen , Liang Tian , Yi Luo , Feng Liu
Laser powder bed fusion (L-PBF) can achieve integrated forming of complex structural components, significantly shortening fabrication processes. This work systematically investigated the effects of L-PBF process parameters and heat treatment on the microstructure and properties of a Cu-Ni-Si alloy. Orthogonal experiments obtained the optimal process parameters for fabricating Cu-Ni-Si alloy bulks by L-PBF. The aging treatment parameters were explored, and the heat treatment process was found to improve the properties of the Cu-Ni-Si alloy. The microstructures and properties of the as-built and heat-treated the Cu-Ni-Si samples were analyzed. The Cu-Ni-Si alloy samples can be fabricated with process parameters of a laser power of 450 W, a scanning speed of 500–800 mm/s, a scanning spacing of 45 μm, and a powder layer thickness of 30 μm. After solid-solution treatment at 920 °C for 1h and subsequent aging at 450 °C for 28h, the Cu-Ni-Si alloy samples show an ultimate tensile strength of 788 MPa and an electrical conductivity of 45.0 % IACS. The nanoscale δ-Ni2Si precipitates are distributed diffusely on the matrix, which contributes to Orowan strengthening in the studied Cu-Ni-Si alloy. These findings provide theoretical guidance for the preparation of high-strength, and high-conductivity Cu-Ni-Si alloys via L-PBF.
{"title":"Effect of heat treatment on the microstructure and properties of a Cu-Ni-Si alloy manufactured by laser powder bed fusion","authors":"Xin Bu , Qian Lei , Xiukuang Zhang , Cong Chen , Liang Tian , Yi Luo , Feng Liu","doi":"10.1016/j.msea.2026.149775","DOIUrl":"10.1016/j.msea.2026.149775","url":null,"abstract":"<div><div>Laser powder bed fusion (L-PBF) can achieve integrated forming of complex structural components, significantly shortening fabrication processes. This work systematically investigated the effects of L-PBF process parameters and heat treatment on the microstructure and properties of a Cu-Ni-Si alloy. Orthogonal experiments obtained the optimal process parameters for fabricating Cu-Ni-Si alloy bulks by L-PBF. The aging treatment parameters were explored, and the heat treatment process was found to improve the properties of the Cu-Ni-Si alloy. The microstructures and properties of the as-built and heat-treated the Cu-Ni-Si samples were analyzed. The Cu-Ni-Si alloy samples can be fabricated with process parameters of a laser power of 450 W, a scanning speed of 500–800 mm/s, a scanning spacing of 45 μm, and a powder layer thickness of 30 μm. After solid-solution treatment at 920 °C for 1h and subsequent aging at 450 °C for 28h, the Cu-Ni-Si alloy samples show an ultimate tensile strength of 788 MPa and an electrical conductivity of 45.0 % IACS. The nanoscale δ-Ni<sub>2</sub>Si precipitates are distributed diffusely on the matrix, which contributes to Orowan strengthening in the studied Cu-Ni-Si alloy. These findings provide theoretical guidance for the preparation of high-strength, and high-conductivity Cu-Ni-Si alloys via L-PBF.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"953 ","pages":"Article 149775"},"PeriodicalIF":7.0,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973665","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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