This study compares the microstructural evolution,dynamic recrystallization(DRX)behavior,tensile properties,and age-hardenability between the newly developed high-speed-extrudable BA56 alloy and those of the widely re...This study compares the microstructural evolution,dynamic recrystallization(DRX)behavior,tensile properties,and age-hardenability between the newly developed high-speed-extrudable BA56 alloy and those of the widely recognized AZ31 alloy in industry.Unlike the AZ31 alloy,which retains partially unrecrystallized grains,the high-speed-extruded BA56 alloy demonstrates a coarser but entirely recrystallized and more homogeneous microstructure.The fine-grained structure and abundant Mg_(3)Bi_(2) particles in the BA56 extrusion billet significantly enhance its DRX behavior,thus enabling rapid and complete recrystallization during extrusion.The BA56 alloy contains band-like fragmented Mg_(3)Bi_(2) particles and numerous fine Mg_(3)Bi_(2) particles distributed throughout the material,in contrast to the sparse Al_(8)Mn_(5) particles in the AZ31 alloy.These features contribute to superior mechanical properties of the BA56 alloy,which achieves tensile yield and ultimate tensile strengths of 205 and 292 MPa,respectively,compared to 196 and 270 MPa for the AZ31 alloy.The superior strength of the BA56 alloy,even with its coarser grain size,can be explained by its elevated Hall-Petch constant and the strengthening contribution from the fine Mg_(3)Bi_(2) particles.Additionally,the BA56 alloy demonstrates significant age-hardenability,achieving a 22%enhancement in hardness following T5 aging,attributed to the precipitation of nanoscale Mg_(3)Bi_(2) and Mg_(17)Al_(12) phases.By contrast,the AZ31 alloy shows minimal hardening due to the absence of precipitate formation during aging.These findings suggest that the BA56 alloy is a promising candidate for the production of extruded Mg components requiring a combination of high productivity,superior mechanical performance,and wide-ranging process adaptability.展开更多
The development of low-cost,high-performance Mg alloys is crucial to the industrial applications of large-scale production of Mg alloys.In this work,extruded Mg-5Bi-3Al alloy with excellent mechanical properties is su...The development of low-cost,high-performance Mg alloys is crucial to the industrial applications of large-scale production of Mg alloys.In this work,extruded Mg-5Bi-3Al alloy with excellent mechanical properties is successfully prepared by modifying the extrusion temperatures(240℃and 300℃).The extruded alloy obtained ultra-high strength(yield strength=380 MPa,ultimate tensile strength=418 MPa)and excellent plasticity(elongation=10.2%)at the extrusion temperature of 240℃,the main contributing factors are primarily attributed to the synergistic effect of ultrafine recrystallized grain size(~0.5µm)and high density of Mg_(3)Bi_(2)precipitates.Stacking faults within the sub-micron Mg_(3)Bi_(2)phase are observed in the E240 alloy,confirming the plastic deformation capability of Mg_(3)Bi_(2)phase.The effects of extrusion temperature on the microstructure,mechanical properties,and work-hardening behavior of the extruded Mg-5Bi-3Al alloys at room temperature are systematically investigated.The results suggest that decreasing the extrusion temperature can refine recrystallized grain size and Mg_(3)Bi_(2)phase size,and the quantity of Mg_(3)Bi_(2)phase is increased,while increasing the extrusion temperature can improve the degree of recrystallization and weaken texture.The work hardening rate is increased with the increased extrusion temperature,mainly due to the coarsening of grains and precipitates,and the weakening of texture.This work provides an experimental basis for preparing high-performance wrought Mg-5Bi-3Al alloys.展开更多
The extrudability,microstructural characteristics,and tensile properties of the Mg–5Bi–3Al(BA53)alloy are investigated herein by comparing them with those of a commercial Mg–8Al–0.5 Zn(AZ80)alloy.When AZ80 is extr...The extrudability,microstructural characteristics,and tensile properties of the Mg–5Bi–3Al(BA53)alloy are investigated herein by comparing them with those of a commercial Mg–8Al–0.5 Zn(AZ80)alloy.When AZ80 is extruded at 400℃,severe hot cracking occurs at exit speeds of 4.5 m/min or more.In contrast,BA53 is successfully extruded without any surface cracking at 400℃ and at high exit speeds of 21–40 m/min.When extruded at 3 m/min(AZ80–3)and 40 m/min(BA53–40),both AZ80 and BA53 exhibited completely recrystallized microstructures with a<10–10>basal texture.However,BA53–40 has a coarser grain structure owing to grain growth promoted by the high temperature in the deformation zone.AZ80–3 contains a continuous network of Mg_(17)Al_(12) particles along the grain boundaries,which form via static precipitation during natural air-cooling after the material exits the extrusion die.BA53–40 contains coarse Mg_(3)Bi_(2) particles aligned parallel to the extrusion direction along with numerous uniformly distributed fine Mg_(3)Bi_(2) particles.AZ80–3 has higher tensile strength than BA53–40 because the relatively finer grains and larger number of solute atoms in AZ80–3 result in stronger grain-boundary and solid-solution hardening effects,respectively.Although BA53 is extruded at a high temperature and extrusion speed of 400℃ and 40 m/min,respectively,the extruded material has a high tensile yield strength of 188 MPa.This can be primarily attributed to the large particle hardening effect resulting from the numerous fine Mg_(3)Bi_(2) particles.展开更多
Effects of Al addition to a Mg±Bi binary alloy on its microstructural characteristics and tensile properties after extrusion are investigated via extrusion of Mg-3Bi±x Al(x=0,1,and 2 wt%)billets and analysis...Effects of Al addition to a Mg±Bi binary alloy on its microstructural characteristics and tensile properties after extrusion are investigated via extrusion of Mg-3Bi±x Al(x=0,1,and 2 wt%)billets and analysis of the extruded materials.The Al addition negligibly affects the second-phase particles of the extruded alloy;however,an increase in the Al content causes significant decreases in the average grain size and maximum texture intensity of the extruded material owing to an increase in the area fraction of dynamically recrystallized(DRXed)grains.The Al addition improves the strength of the extruded alloy;this improvement is attributed to the enhanced grain-boundary hardening and solid-solution hardening effects induced by grain refinement and Al solute atoms,respectively.As the Al content increases from 0 wt%to 1 wt%and 2 wt%,the tensile elongation increases substantially from 2.8%to 9.4%and 16.9%,respectively.The reduction in the number and size of un DRXed grains with increasing Al content suppresses the formation and coalescence of cracks in the un DRXed grains during tension,which results in a significant improvement in the tensile ductility of the extruded material.During tensile deformation,large undesirable twins that act as crack initiation sites are locally formed in the un DRXed grains of the Mg-3Bi alloy,whereas relatively smaller twins are uniformly formed in both the DRXed and the un DRXed grains of the Mg-3Bi-2Al alloy.Consequently,the extruded Mg-3Bi-2Al alloy has a substantially higher tensile yield strength±elongation product(2924 MPa%)than the extruded Al-free B3 alloy(381 MPa%).展开更多
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korea government(MSIT)(Nos.RS-2024–00351052 and RS-2024–00450561).
文摘This study compares the microstructural evolution,dynamic recrystallization(DRX)behavior,tensile properties,and age-hardenability between the newly developed high-speed-extrudable BA56 alloy and those of the widely recognized AZ31 alloy in industry.Unlike the AZ31 alloy,which retains partially unrecrystallized grains,the high-speed-extruded BA56 alloy demonstrates a coarser but entirely recrystallized and more homogeneous microstructure.The fine-grained structure and abundant Mg_(3)Bi_(2) particles in the BA56 extrusion billet significantly enhance its DRX behavior,thus enabling rapid and complete recrystallization during extrusion.The BA56 alloy contains band-like fragmented Mg_(3)Bi_(2) particles and numerous fine Mg_(3)Bi_(2) particles distributed throughout the material,in contrast to the sparse Al_(8)Mn_(5) particles in the AZ31 alloy.These features contribute to superior mechanical properties of the BA56 alloy,which achieves tensile yield and ultimate tensile strengths of 205 and 292 MPa,respectively,compared to 196 and 270 MPa for the AZ31 alloy.The superior strength of the BA56 alloy,even with its coarser grain size,can be explained by its elevated Hall-Petch constant and the strengthening contribution from the fine Mg_(3)Bi_(2) particles.Additionally,the BA56 alloy demonstrates significant age-hardenability,achieving a 22%enhancement in hardness following T5 aging,attributed to the precipitation of nanoscale Mg_(3)Bi_(2) and Mg_(17)Al_(12) phases.By contrast,the AZ31 alloy shows minimal hardening due to the absence of precipitate formation during aging.These findings suggest that the BA56 alloy is a promising candidate for the production of extruded Mg components requiring a combination of high productivity,superior mechanical performance,and wide-ranging process adaptability.
基金supported by the National Natural Science Foundation of China[grant nos.52371005,52022017,and 51927801]Fundamental Research Funds for the Central Universities.E.G.thanks Xiaomi Foundation for support.
文摘The development of low-cost,high-performance Mg alloys is crucial to the industrial applications of large-scale production of Mg alloys.In this work,extruded Mg-5Bi-3Al alloy with excellent mechanical properties is successfully prepared by modifying the extrusion temperatures(240℃and 300℃).The extruded alloy obtained ultra-high strength(yield strength=380 MPa,ultimate tensile strength=418 MPa)and excellent plasticity(elongation=10.2%)at the extrusion temperature of 240℃,the main contributing factors are primarily attributed to the synergistic effect of ultrafine recrystallized grain size(~0.5µm)and high density of Mg_(3)Bi_(2)precipitates.Stacking faults within the sub-micron Mg_(3)Bi_(2)phase are observed in the E240 alloy,confirming the plastic deformation capability of Mg_(3)Bi_(2)phase.The effects of extrusion temperature on the microstructure,mechanical properties,and work-hardening behavior of the extruded Mg-5Bi-3Al alloys at room temperature are systematically investigated.The results suggest that decreasing the extrusion temperature can refine recrystallized grain size and Mg_(3)Bi_(2)phase size,and the quantity of Mg_(3)Bi_(2)phase is increased,while increasing the extrusion temperature can improve the degree of recrystallization and weaken texture.The work hardening rate is increased with the increased extrusion temperature,mainly due to the coarsening of grains and precipitates,and the weakening of texture.This work provides an experimental basis for preparing high-performance wrought Mg-5Bi-3Al alloys.
基金supported by the National Research Foundation of Korea(NRF)grant(No.2019R1A2C1085272)funded by the Ministry of Science,ICT,and Future Planning(MSIP,South Korea)by the Materials and Components Technology Development Program(No.20011091)funded by the Ministry of Trade,Industry,and Energy(MOTIE,South Korea)。
文摘The extrudability,microstructural characteristics,and tensile properties of the Mg–5Bi–3Al(BA53)alloy are investigated herein by comparing them with those of a commercial Mg–8Al–0.5 Zn(AZ80)alloy.When AZ80 is extruded at 400℃,severe hot cracking occurs at exit speeds of 4.5 m/min or more.In contrast,BA53 is successfully extruded without any surface cracking at 400℃ and at high exit speeds of 21–40 m/min.When extruded at 3 m/min(AZ80–3)and 40 m/min(BA53–40),both AZ80 and BA53 exhibited completely recrystallized microstructures with a<10–10>basal texture.However,BA53–40 has a coarser grain structure owing to grain growth promoted by the high temperature in the deformation zone.AZ80–3 contains a continuous network of Mg_(17)Al_(12) particles along the grain boundaries,which form via static precipitation during natural air-cooling after the material exits the extrusion die.BA53–40 contains coarse Mg_(3)Bi_(2) particles aligned parallel to the extrusion direction along with numerous uniformly distributed fine Mg_(3)Bi_(2) particles.AZ80–3 has higher tensile strength than BA53–40 because the relatively finer grains and larger number of solute atoms in AZ80–3 result in stronger grain-boundary and solid-solution hardening effects,respectively.Although BA53 is extruded at a high temperature and extrusion speed of 400℃ and 40 m/min,respectively,the extruded material has a high tensile yield strength of 188 MPa.This can be primarily attributed to the large particle hardening effect resulting from the numerous fine Mg_(3)Bi_(2) particles.
基金a National Research Foundation of Korea(NRF)grant funded by the Ministry of Science,ICT and Future Planning(MSIP,South Korea)(No.2019R1A2C1085272)by the Materials and Components Technology Development Program of the Ministry of Trade,Industry and Energy(MOTIE,South Korea)(No.20011091)。
文摘Effects of Al addition to a Mg±Bi binary alloy on its microstructural characteristics and tensile properties after extrusion are investigated via extrusion of Mg-3Bi±x Al(x=0,1,and 2 wt%)billets and analysis of the extruded materials.The Al addition negligibly affects the second-phase particles of the extruded alloy;however,an increase in the Al content causes significant decreases in the average grain size and maximum texture intensity of the extruded material owing to an increase in the area fraction of dynamically recrystallized(DRXed)grains.The Al addition improves the strength of the extruded alloy;this improvement is attributed to the enhanced grain-boundary hardening and solid-solution hardening effects induced by grain refinement and Al solute atoms,respectively.As the Al content increases from 0 wt%to 1 wt%and 2 wt%,the tensile elongation increases substantially from 2.8%to 9.4%and 16.9%,respectively.The reduction in the number and size of un DRXed grains with increasing Al content suppresses the formation and coalescence of cracks in the un DRXed grains during tension,which results in a significant improvement in the tensile ductility of the extruded material.During tensile deformation,large undesirable twins that act as crack initiation sites are locally formed in the un DRXed grains of the Mg-3Bi alloy,whereas relatively smaller twins are uniformly formed in both the DRXed and the un DRXed grains of the Mg-3Bi-2Al alloy.Consequently,the extruded Mg-3Bi-2Al alloy has a substantially higher tensile yield strength±elongation product(2924 MPa%)than the extruded Al-free B3 alloy(381 MPa%).
