Pub Date : 2025-04-15DOI: 10.1016/j.msea.2025.148297
S.P. Zhao , L. Lu , X.T. Zou , J.F. Zhao , N.B. Zhang , Y. Cai , Xu Zhang , S.N. Luo
Impact response of a solution-treated hot-rolled Inconel 718 superalloy is investigated with plate impact experiments and crystal plasticity finite element modeling. Free surface velocity measurements are conducted along with postmortem microstructure characterizations. The Hugoniot equation of state is determined up to 21 GPa. Dislocation slips, stacking faults and Lomer–Cottrell dislocation locks are predominant deformation mechanisms. A crystal plasticity model considering thermal activation and dislocation drag is developed to simulate shock compression and spallation of the superalloy. This constitutive model reproduces the measured free surface velocity histories. During shock compression, the contributions of 12 independent slip systems to plastic deformation are approximately equal, and plastic strain mainly concentrates at grain boundaries or annealing twin boundaries. There is an increase in the number of active slip systems at higher impact velocities. Simulations reveal both intergranular and intragranular micro-cracks at the primary stage of damage evolution, where intergranular cracks are predominant, consistent with experiments. The present research provides insights into and a useful modeling case for understanding high strain rate deformation and spallation of Inconel 718 superalloy.
{"title":"Plate impact experiments and crystal plasticity finite element modeling of solution-treated Inconel 718 superalloy","authors":"S.P. Zhao , L. Lu , X.T. Zou , J.F. Zhao , N.B. Zhang , Y. Cai , Xu Zhang , S.N. Luo","doi":"10.1016/j.msea.2025.148297","DOIUrl":"10.1016/j.msea.2025.148297","url":null,"abstract":"<div><div>Impact response of a solution-treated hot-rolled Inconel 718 superalloy is investigated with plate impact experiments and crystal plasticity finite element modeling. Free surface velocity measurements are conducted along with postmortem microstructure characterizations. The Hugoniot equation of state is determined up to 21 GPa. Dislocation slips, stacking faults and Lomer–Cottrell dislocation locks are predominant deformation mechanisms. A crystal plasticity model considering thermal activation and dislocation drag is developed to simulate shock compression and spallation of the superalloy. This constitutive model reproduces the measured free surface velocity histories. During shock compression, the contributions of 12 independent slip systems to plastic deformation are approximately equal, and plastic strain mainly concentrates at grain boundaries or annealing twin boundaries. There is an increase in the number of active slip systems at higher impact velocities. Simulations reveal both intergranular and intragranular micro-cracks at the primary stage of damage evolution, where intergranular cracks are predominant, consistent with experiments. The present research provides insights into and a useful modeling case for understanding high strain rate deformation and spallation of Inconel 718 superalloy.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"934 ","pages":"Article 148297"},"PeriodicalIF":6.1,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850789","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 : 2025-04-15DOI: 10.1016/j.msea.2025.148347
Shebeer A. Rahim , Joseph Tomei , Joseph Licavoli , Hamid R. Bakhsheshi-Rad , Jeremy Goldman , Jaroslaw W. Drelich
Biodegradable metallic stents that dissolve over time are essential for treating vascular artery disease. Previous designs made from polymers and magnesium have not achieved the required mechanical properties and degradation patterns. Here, we report a novel zinc alloy that possesses a combination of high strength, good ductility, and uniform degradation behavior. The Zn-0.9Cu-0.4Mn-0.01 Mg alloy is produced using melt spinning (a rapid solidification technique), compaction, and extrusion to enhance the synergy between strength and ductility. The melt-spun extruded alloy exhibits an elongation to failure of nearly 30 % and a tensile strength exceeding 320 MPa, meeting the mechanical performance criteria required for vascular stenting materials. Melt spinning results in weak texture facilitating basal slip dislocations, and promoting ductility, while maintaining high strength. The microstructure of the melt-spun alloy displays a more uniform and finer microstructure as compared to the extruded alloy. The fine grain size and the uniform dispersion of secondary phases contribute to the uniform degradation behavior of the melt-spun extruded alloy, with a corrosion rate of ∼0.6 mm/year and low corrosion current density of ∼40 μA/cm2. The findings suggest that rapid solidification of zinc alloys through melt spinning is a promising approach for developing biodegradable medical implants of predictable degradation.
{"title":"Microstructural control of Zn alloy by melt spinning - A novel approach towards fabrication of advanced biodegradable biomedical materials","authors":"Shebeer A. Rahim , Joseph Tomei , Joseph Licavoli , Hamid R. Bakhsheshi-Rad , Jeremy Goldman , Jaroslaw W. Drelich","doi":"10.1016/j.msea.2025.148347","DOIUrl":"10.1016/j.msea.2025.148347","url":null,"abstract":"<div><div>Biodegradable metallic stents that dissolve over time are essential for treating vascular artery disease. Previous designs made from polymers and magnesium have not achieved the required mechanical properties and degradation patterns. Here, we report a novel zinc alloy that possesses a combination of high strength, good ductility, and uniform degradation behavior. The Zn-0.9Cu-0.4Mn-0.01 Mg alloy is produced using melt spinning (a rapid solidification technique), compaction, and extrusion to enhance the synergy between strength and ductility. The melt-spun extruded alloy exhibits an elongation to failure of nearly 30 % and a tensile strength exceeding 320 MPa, meeting the mechanical performance criteria required for vascular stenting materials. Melt spinning results in weak texture facilitating basal slip dislocations, and promoting ductility, while maintaining high strength. The microstructure of the melt-spun alloy displays a more uniform and finer microstructure as compared to the extruded alloy. The fine grain size and the uniform dispersion of secondary phases contribute to the uniform degradation behavior of the melt-spun extruded alloy, with a corrosion rate of ∼0.6 mm/year and low corrosion current density of ∼40 μA/cm<sup>2</sup>. The findings suggest that rapid solidification of zinc alloys through melt spinning is a promising approach for developing biodegradable medical implants of predictable degradation.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"934 ","pages":"Article 148347"},"PeriodicalIF":6.1,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143839800","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 : 2025-04-14DOI: 10.1016/j.msea.2025.148345
Junlei Zhang , Xinhai Hou , Zulai Li , Xiang Chen , Guangsheng Huang , Weizhang Wang
In this work, selective tungsten inert gas (TIG) arc remelting was applied to the nugget zone (NZ) side or NZ middle of a friction stir welding (FSW) AZ31 Magnesium joint, with the aim to explore the impacts of localized remelting positions on microstructure and mechanical properties, as well as to uncover the relationship between mechanical behavior and microstructure of the joints. It was found that the TIG arc treatment contributed to a random texture distribution within the TIG melting zone and a reduction of residual dislocations in the microstructure. The resultant mechanical properties were significantly enhanced, particularly elongation (EL) and ultimate tensile strength (UTS). Notably, remelting at NZ side yielded superior properties compared to the NZ middle, with UTS and EL increasing from 5.5 % to 201 MPa in the initial joint to 13.3 % and 238 MPa, representing an increase of 18.4 % and 123 %, respectively. The improved mechanical properties were primarily related to the weakened strain localization.
{"title":"Influence of localized selective remelting positions on mechanical properties and deformation behavior of friction stir welding AZ31 Mg joint","authors":"Junlei Zhang , Xinhai Hou , Zulai Li , Xiang Chen , Guangsheng Huang , Weizhang Wang","doi":"10.1016/j.msea.2025.148345","DOIUrl":"10.1016/j.msea.2025.148345","url":null,"abstract":"<div><div>In this work, selective tungsten inert gas (TIG) arc remelting was applied to the nugget zone (NZ) side or NZ middle of a friction stir welding (FSW) AZ31 Magnesium joint, with the aim to explore the impacts of localized remelting positions on microstructure and mechanical properties, as well as to uncover the relationship between mechanical behavior and microstructure of the joints. It was found that the TIG arc treatment contributed to a random texture distribution within the TIG melting zone and a reduction of residual dislocations in the microstructure. The resultant mechanical properties were significantly enhanced, particularly elongation (EL) and ultimate tensile strength (UTS). Notably, remelting at NZ side yielded superior properties compared to the NZ middle, with UTS and EL increasing from 5.5 % to 201 MPa in the initial joint to 13.3 % and 238 MPa, representing an increase of 18.4 % and 123 %, respectively. The improved mechanical properties were primarily related to the weakened strain localization.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"934 ","pages":"Article 148345"},"PeriodicalIF":6.1,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834150","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 : 2025-04-14DOI: 10.1016/j.msea.2025.148331
F. Chen , Y.J. Huang , H. Wang , Y.N. Jiang , Q.Q. Zeng
Typically, the influence of compressive stress has been seldom considered during the creep aging process (CAF) of thin-walled components. However, the inclusion of stiffener is known to greatly enhance the compressive stress during CAF, and the influence of compressive stress cannot be ignored. In this work, the tensile creep aging (TCA) and compressive creep aging (CCA) behavior and microstructure evolution were investigated under varying stresses, employing the 2195-T34 Al-Li alloy as the target material. A statistical analysis reveals a disparity in the creep strains of TCA and CCA. Under reduced stress conditions, the creep strain of the former exceeds that of the latter, and the degree of asymmetry gradually decreases as stress levels increase. The asymmetry in the strength of the creep-aged specimens was also observed, with the TCA specimens exhibiting more strength than the CCA specimens and the asymmetry in strength decreased with increasing stress. The stress exponents of TCA and CCA were determined to be n = 0.88 and n = 2.23 respectively, and the creep mechanisms of the two specimens exhibited distinct differences. Microstructural analysis revealed a more pronounced Cu-rich phase at the grain boundaries of the TCA specimens, leading to a reduction in the elongation of the specimens, which was confirmed by differences in fracture morphology. The CCA specimens had a higher concentration of θ′ phases, and the number of these phases declined as the stress increased, which is consistent with the result that the strength of the CCA specimens improved with increasing stress. Furthermore, a constitutive model derived from tensile/compression creep curves is proposed, and the calculated results and actual data exhibit remarkable agreement.
{"title":"Tensile/compression creep aging behavior of 2195-T34 Al-Li alloy under different stress levels","authors":"F. Chen , Y.J. Huang , H. Wang , Y.N. Jiang , Q.Q. Zeng","doi":"10.1016/j.msea.2025.148331","DOIUrl":"10.1016/j.msea.2025.148331","url":null,"abstract":"<div><div>Typically, the influence of compressive stress has been seldom considered during the creep aging process (CAF) of thin-walled components. However, the inclusion of stiffener is known to greatly enhance the compressive stress during CAF, and the influence of compressive stress cannot be ignored. In this work, the tensile creep aging (TCA) and compressive creep aging (CCA) behavior and microstructure evolution were investigated under varying stresses, employing the 2195-T34 Al-Li alloy as the target material. A statistical analysis reveals a disparity in the creep strains of TCA and CCA. Under reduced stress conditions, the creep strain of the former exceeds that of the latter, and the degree of asymmetry gradually decreases as stress levels increase. The asymmetry in the strength of the creep-aged specimens was also observed, with the TCA specimens exhibiting more strength than the CCA specimens and the asymmetry in strength decreased with increasing stress. The stress exponents of TCA and CCA were determined to be n = 0.88 and n = 2.23 respectively, and the creep mechanisms of the two specimens exhibited distinct differences. Microstructural analysis revealed a more pronounced Cu-rich phase at the grain boundaries of the TCA specimens, leading to a reduction in the elongation of the specimens, which was confirmed by differences in fracture morphology. The CCA specimens had a higher concentration of θ′ phases, and the number of these phases declined as the stress increased, which is consistent with the result that the strength of the CCA specimens improved with increasing stress. Furthermore, a constitutive model derived from tensile/compression creep curves is proposed, and the calculated results and actual data exhibit remarkable agreement.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"935 ","pages":"Article 148331"},"PeriodicalIF":6.1,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855820","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 : 2025-04-14DOI: 10.1016/j.msea.2025.148346
Yanfei Chen , Zhengqiang Zhu , M. Amir Siddiq , Ke Li , Fanrong Ai , Zhigang Wang
The softening of the heat-affected zone (HAZ) is a major factor contributing to the failure of welded joints in magnesium (Mg) alloys. Therefore, reducing heat input and minimizing the extent of the HAZ are critical for achieving high-quality Mg alloy joints. This study introduces a novel ultrasonic-assisted solid-state welding process to join 0.7 mm thick Mg alloy plates while minimizing strength degradation. The process focuses on precise temperature control and the evolution of intermetallic compounds (IMCs) within the HAZ, thermo-mechanically affected zone (TMAZ), and nugget zone, effectively suppressing phase transformations and significantly narrowing the HAZ. The results reveal an almost imperceptible HAZ in the welded joints. Additionally, grain refinement occurred within the nugget zone and up to 100 μm from the nugget boundary, with grain sizes measuring approximately 10 μm. Simultaneously, IMCs in these regions, composed of both rare-earth and conventional elements, were fragmented into micron/submicron-sized particles and uniformly dispersed throughout the joint, facilitated by ultrasonic vibrations. As a result, the welded joint exhibited superior mechanical performance, achieving a tensile-shear strength of 97.8 % of the base metal. These findings provide valuable insights into the strength enhancement achieved in ultrasonically welded joints, presenting a promising approach for mitigating strength loss in Mg alloy welding.
{"title":"Minimal strength loss and corresponding mechanisms in the ultrasonic joining of magnesium alloys","authors":"Yanfei Chen , Zhengqiang Zhu , M. Amir Siddiq , Ke Li , Fanrong Ai , Zhigang Wang","doi":"10.1016/j.msea.2025.148346","DOIUrl":"10.1016/j.msea.2025.148346","url":null,"abstract":"<div><div>The softening of the heat-affected zone (HAZ) is a major factor contributing to the failure of welded joints in magnesium (Mg) alloys. Therefore, reducing heat input and minimizing the extent of the HAZ are critical for achieving high-quality Mg alloy joints. This study introduces a novel ultrasonic-assisted solid-state welding process to join 0.7 mm thick Mg alloy plates while minimizing strength degradation. The process focuses on precise temperature control and the evolution of intermetallic compounds (IMCs) within the HAZ, thermo-mechanically affected zone (TMAZ), and nugget zone, effectively suppressing phase transformations and significantly narrowing the HAZ. The results reveal an almost imperceptible HAZ in the welded joints. Additionally, grain refinement occurred within the nugget zone and up to 100 μm from the nugget boundary, with grain sizes measuring approximately 10 μm. Simultaneously, IMCs in these regions, composed of both rare-earth and conventional elements, were fragmented into micron/submicron-sized particles and uniformly dispersed throughout the joint, facilitated by ultrasonic vibrations. As a result, the welded joint exhibited superior mechanical performance, achieving a tensile-shear strength of 97.8 % of the base metal. These findings provide valuable insights into the strength enhancement achieved in ultrasonically welded joints, presenting a promising approach for mitigating strength loss in Mg alloy welding.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"934 ","pages":"Article 148346"},"PeriodicalIF":6.1,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834151","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 : 2025-04-14DOI: 10.1016/j.msea.2025.148344
Z.P. Jia , X.J. Guan , F. Shi , X.W. Li
The influence of grain boundary engineering (GBE) on the mechanical properties of FeCoCrNi high-entropy alloy (HEA) at different temperatures was systematically examined. An optimal GBE process, namely cold rolling (with 5 % reduction) followed by annealing (at 900 °C for 4 h), was ascertained to markedly modify the grain boundary character distribution (GBCD) in the alloy, and significantly increase the fraction of special boundaries (Σ3-Σ29) to as high as 82.4 %, and meanwhile, the connectivity of random high-angle grain boundaries (RHAGBs) has been effectively disrupted. Such a modified GBCD leads to an improvement in room-temperature tensile ductility without loss of strength, but to a simultaneous enhancement in strength and ductility at high temperatures (600 °C–800 °C). The improved properties result mainly from the inducement of abundant Σ3 boundaries that effectively inhibit intergranular crack initiation and propagation during plastic deformation. Also, the GBE process optimizes deformation uniformity, mitigates dynamic recovery and recrystallization and suppresses dynamic strain aging at high temperatures, further facilitating more stable and homogeneous plastic deformation. This study has offered a detailed perspective on how GBE affects the plastic deformation and damage behavior of FeCoCrNi HEA at different temperatures, thus providing a novel pathway to improve the mechanical properties of HEA especially at high temperatures.
{"title":"An optimal grain boundary engineering approach to improving the mechanical properties of FeCoCrNi high-entropy alloys at different temperatures","authors":"Z.P. Jia , X.J. Guan , F. Shi , X.W. Li","doi":"10.1016/j.msea.2025.148344","DOIUrl":"10.1016/j.msea.2025.148344","url":null,"abstract":"<div><div>The influence of grain boundary engineering (GBE) on the mechanical properties of FeCoCrNi high-entropy alloy (HEA) at different temperatures was systematically examined. An optimal GBE process, namely cold rolling (with 5 % reduction) followed by annealing (at 900 °C for 4 h), was ascertained to markedly modify the grain boundary character distribution (GBCD) in the alloy, and significantly increase the fraction of special boundaries (Σ3-Σ29) to as high as 82.4 %, and meanwhile, the connectivity of random high-angle grain boundaries (RHAGBs) has been effectively disrupted. Such a modified GBCD leads to an improvement in room-temperature tensile ductility without loss of strength, but to a simultaneous enhancement in strength and ductility at high temperatures (600 °C–800 °C). The improved properties result mainly from the inducement of abundant Σ3 boundaries that effectively inhibit intergranular crack initiation and propagation during plastic deformation. Also, the GBE process optimizes deformation uniformity, mitigates dynamic recovery and recrystallization and suppresses dynamic strain aging at high temperatures, further facilitating more stable and homogeneous plastic deformation. This study has offered a detailed perspective on how GBE affects the plastic deformation and damage behavior of FeCoCrNi HEA at different temperatures, thus providing a novel pathway to improve the mechanical properties of HEA especially at high temperatures.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"934 ","pages":"Article 148344"},"PeriodicalIF":6.1,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143839797","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 : 2025-04-14DOI: 10.1016/j.msea.2025.148343
Daobin Zhang , Mujin Yang , Jiang Yi , Zhifu Yao , Minglin He , Hailin Cao , Yuqing Hu , Xingjun Liu , Shuai Wang
This work investigates the effects of electric pulse treatment (EPT) on the microstructure and mechanical properties of cold-rolled 20Cr ferritic alloy, employing quasi-in-situ uniaxial tension, electron backscattered diffraction (EBSD), transmission electron microscopy (TEM), and atom probe tomography (APT). Uniaxial tensile tests indicate that an optimal strength-ductility synergy is achieved with pulse parameters of 420 A and 300 Hz, resulting in a tensile strength of 1250 MPa and an elongation at break of 7 %. Excessive peak current or frequency leads to a sharp decrease in strength, while lower current or frequency fails to restore ductility. Short-duration EPT significantly enhance hardness through the dense precipitation of superfine Ni16Ti6Si7-G phase particles, while the coordinated deformation of lamellar and fine grains moderately improved ductility. Additionally, EBSD analysis during quasi-in-situ tension reveals that the fine grain zones between lamellar grains play a crucial role in work hardening, whereas the lamellar grains tend to undergo work softening at an earlier stage. The study concludes that EPT effectively enhances the mechanical performance of 20Cr ferritic alloy through G-phase precipitation, providing a promising approach for optimizing the strength-ductility balance.
{"title":"G-phase precipitation via electric pulse and its effect on the strength-ductility synergy","authors":"Daobin Zhang , Mujin Yang , Jiang Yi , Zhifu Yao , Minglin He , Hailin Cao , Yuqing Hu , Xingjun Liu , Shuai Wang","doi":"10.1016/j.msea.2025.148343","DOIUrl":"10.1016/j.msea.2025.148343","url":null,"abstract":"<div><div>This work investigates the effects of electric pulse treatment (EPT) on the microstructure and mechanical properties of cold-rolled 20Cr ferritic alloy, employing quasi-in-situ uniaxial tension, electron backscattered diffraction (EBSD), transmission electron microscopy (TEM), and atom probe tomography (APT). Uniaxial tensile tests indicate that an optimal strength-ductility synergy is achieved with pulse parameters of 420 A and 300 Hz, resulting in a tensile strength of 1250 MPa and an elongation at break of 7 %. Excessive peak current or frequency leads to a sharp decrease in strength, while lower current or frequency fails to restore ductility. Short-duration EPT significantly enhance hardness through the dense precipitation of superfine Ni<sub>16</sub>Ti<sub>6</sub>Si<sub>7</sub>-G phase particles, while the coordinated deformation of lamellar and fine grains moderately improved ductility. Additionally, EBSD analysis during quasi-in-situ tension reveals that the fine grain zones between lamellar grains play a crucial role in work hardening, whereas the lamellar grains tend to undergo work softening at an earlier stage. The study concludes that EPT effectively enhances the mechanical performance of 20Cr ferritic alloy through G-phase precipitation, providing a promising approach for optimizing the strength-ductility balance.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"934 ","pages":"Article 148343"},"PeriodicalIF":6.1,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834152","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}
In this work, a detailed investigation of creep and stress rupture behaviour was carried out on laser powder bed fusion processed Hastelloy X in two orthogonal directions, i.e., vertical (along build direction) and horizontal (perpendicular to build direction). Stress-relieve treatment (1050°C for 1 h) was performed on as-built specimens prior to creep tests. High values of creep parameters, such as apparent stress exponent, , and apparent activation energy, , for vertical ( = 8.1 and = 464 kJ/mol) and horizontal ( = 6.7 and = 548 kJ/mol) specimens in the stress range of 75–150 MPa and the temperature range of 750–800°C indicated the presence of a threshold stress. This threshold stress originated from the obstructed dislocation motion by M6C, M23C6, σ and μ phases, which dynamically formed during long-term thermal exposure. By appropriate evaluation of the threshold stress and subtracting it from the applied stress, the stress exponent values decreased to 4.5 for both vertical and horizontal specimens, respectively, indicating dislocation climb as the underlying deformation mechanism. Still, the creep and stress rupture properties were notably superior in the vertically oriented samples compared to the horizontally oriented ones. This difference was primarily attributed to the columnar grain morphology observed in the vertically oriented specimen, as opposed to the more equiaxed morphology in the horizontally oriented specimen.
{"title":"Anisotropic creep and stress rupture behaviour of laser powder bed fusion processed Hastelloy X","authors":"Shavi Agrawal , Chandan Kumar , G.S. Avadhani , Martin Heilmaier , Satyam Suwas","doi":"10.1016/j.msea.2025.148342","DOIUrl":"10.1016/j.msea.2025.148342","url":null,"abstract":"<div><div>In this work, a detailed investigation of creep and stress rupture behaviour was carried out on laser powder bed fusion processed Hastelloy X in two orthogonal directions, i.e., vertical (along build direction) and horizontal (perpendicular to build direction). Stress-relieve treatment (1050°C for 1 h) was performed on as-built specimens prior to creep tests. High values of creep parameters, such as apparent stress exponent, <span><math><mrow><msub><mi>n</mi><mi>a</mi></msub></mrow></math></span>, and apparent activation energy, <span><math><mrow><msub><mi>Q</mi><mi>a</mi></msub></mrow></math></span>, for vertical (<span><math><mrow><msub><mi>n</mi><mi>a</mi></msub></mrow></math></span> = 8.1 and <span><math><mrow><msub><mi>Q</mi><mi>a</mi></msub></mrow></math></span> = 464 kJ/mol) and horizontal (<span><math><mrow><msub><mi>n</mi><mi>a</mi></msub></mrow></math></span> = 6.7 and <span><math><mrow><msub><mi>Q</mi><mi>a</mi></msub></mrow></math></span> = 548 kJ/mol) specimens in the stress range of 75–150 MPa and the temperature range of 750–800°C indicated the presence of a threshold stress. This threshold stress originated from the obstructed dislocation motion by M<sub>6</sub>C, M<sub>23</sub>C<sub>6</sub>, σ and μ phases, which dynamically formed during long-term thermal exposure. By appropriate evaluation of the threshold stress and subtracting it from the applied stress, the stress exponent values decreased to 4.5 for both vertical and horizontal specimens, respectively, indicating dislocation climb as the underlying deformation mechanism. Still, the creep and stress rupture properties were notably superior in the vertically oriented samples compared to the horizontally oriented ones. This difference was primarily attributed to the columnar grain morphology observed in the vertically oriented specimen, as opposed to the more equiaxed morphology in the horizontally oriented specimen.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"934 ","pages":"Article 148342"},"PeriodicalIF":6.1,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848388","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 : 2025-04-12DOI: 10.1016/j.msea.2025.148330
Yingzhi Liang , Tianle Li , Xiang Wu , Xiaochun Liu
Highly deformed cold-drawn pearlitic steel wires are well-known for the high strength, but with very limited tensile elongation (typically below 3 %). In this study, we developed an efficient way of recovering tensile elongation up to triple through low-temperature annealing at 275 °C for 30 min, i.e., the tensile strength of the pearlite steel wires remains almost unchanged (∼2088 MPa) while the tensile elongation increases from 2.1 % to 8.8 %. In comparison to the cold-drawn state pearlite consisting of highly orientated nanoscale laminates with sharp interfaces between ferrite and cementite, we found that low-temperature annealing promotes a carbon partitioning from cementite to adjacent ferrite grains, resulting in the formation of carbon concentration gradient across cementite/ferrite boundaries. The diffused boundaries may relieve the stress concentration during plastic deformation, facilitating the transmission of mobile dislocations across boundaries, making the high-strength pearlite steel ductile. The findings in this study may provide a general routine of ductile high-strength materials through boundary composition and structural configuring.
{"title":"Making high strength pearlite steel ductile by engineering boundary carbon concentration gradient at low temperature","authors":"Yingzhi Liang , Tianle Li , Xiang Wu , Xiaochun Liu","doi":"10.1016/j.msea.2025.148330","DOIUrl":"10.1016/j.msea.2025.148330","url":null,"abstract":"<div><div>Highly deformed cold-drawn pearlitic steel wires are well-known for the high strength, but with very limited tensile elongation (typically below 3 %). In this study, we developed an efficient way of recovering tensile elongation up to triple through low-temperature annealing at 275 °C for 30 min, i.e., the tensile strength of the pearlite steel wires remains almost unchanged (∼2088 MPa) while the tensile elongation increases from 2.1 % to 8.8 %. In comparison to the cold-drawn state pearlite consisting of highly orientated nanoscale laminates with sharp interfaces between ferrite and cementite, we found that low-temperature annealing promotes a carbon partitioning from cementite to adjacent ferrite grains, resulting in the formation of carbon concentration gradient across cementite/ferrite boundaries. The diffused boundaries may relieve the stress concentration during plastic deformation, facilitating the transmission of mobile dislocations across boundaries, making the high-strength pearlite steel ductile. The findings in this study may provide a general routine of ductile high-strength materials through boundary composition and structural configuring.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"935 ","pages":"Article 148330"},"PeriodicalIF":6.1,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855821","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 : 2025-04-12DOI: 10.1016/j.msea.2025.148304
Brandon Ohl , Carelyn Campbell , David C. Dunand
A machine-learning model was built to predict the strain rate in the steady-state regime of any γ′ strengthened Co-based superalloy as a function of temperature and stress, given inputs of alloy composition, heat treatments, and microstructure (γ′ precipitate volume fraction). The model is trained on nearly 1000 distinct γ/γ′ strengthened Co-based superalloys reported in the recent literature. We developed additional intermediary machine-learning (ML) models, requiring only a compositional input, for six materials properties: solvus-, solidus-, and liquidus temperatures, peak hardness, as well as lattice misfit and yield strength (at ambient and elevated temperature). These intermediate material properties results are fed back into the ML model to improve the accuracy of creep prediction. Finally, we validate the model by predicting intermediate properties and creep properties for 16 new alloys with an alloying element outside the training data, for which we then experimentally determine these values. The results suggest that this method produces a model which provides valuable screening data for exploring the compositional design space—even when lacking training data in that space—but it is not accurate enough to use in full replacement of experimental measurements.
{"title":"Machine-learning prediction of creep strain rate in γ/γ′ cobalt-based superalloys","authors":"Brandon Ohl , Carelyn Campbell , David C. Dunand","doi":"10.1016/j.msea.2025.148304","DOIUrl":"10.1016/j.msea.2025.148304","url":null,"abstract":"<div><div>A machine-learning model was built to predict the strain rate in the steady-state regime of any γ′ strengthened Co-based superalloy as a function of temperature and stress, given inputs of alloy composition, heat treatments, and microstructure (γ′ precipitate volume fraction). The model is trained on nearly 1000 distinct γ/γ′ strengthened Co-based superalloys reported in the recent literature. We developed additional intermediary machine-learning (ML) models, requiring only a compositional input, for six materials properties: solvus-, solidus-, and liquidus temperatures, peak hardness, as well as lattice misfit and yield strength (at ambient and elevated temperature). These intermediate material properties results are fed back into the ML model to improve the accuracy of creep prediction. Finally, we validate the model by predicting intermediate properties and creep properties for 16 new alloys with an alloying element outside the training data, for which we then experimentally determine these values. The results suggest that this method produces a model which provides valuable screening data for exploring the compositional design space—even when lacking training data in that space—but it is not accurate enough to use in full replacement of experimental measurements.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"934 ","pages":"Article 148304"},"PeriodicalIF":6.1,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143844457","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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