The effect of different extrusion parameters on the microstructure and mechanical properties of Mg-4Sm-3Gd-2Yb-0.5Zr(SGY2)alloy was investigated.It was observed that under different extrusion parameters,unDRXed grains...The effect of different extrusion parameters on the microstructure and mechanical properties of Mg-4Sm-3Gd-2Yb-0.5Zr(SGY2)alloy was investigated.It was observed that under different extrusion parameters,unDRXed grains of SGY2 alloy exhibited a pronounced basal plane texture,specifically<01.10>//ED,while the texture of DRXed grains was relatively dispersed.Under the condition of 420℃ and an extrusion ratio of 9.4(420℃-ER9.4),the basal plane texture intensity of unDRXed grains in SGY2 alloy was the highest.Furthermore,SGY2 alloy at different extrusion parameters exhibited recrystallization mechanisms mainly characterized by continuous dynamic recrystallization(CDRX),with some DRXed grains and deformed grains experiencing discontinuous dynamic recrystallization(DDRX).Additionally,at the 420℃-ER9.4,the second phase particles in the as-extruded SGY2 alloy were smaller in size and exhibited a dispersed distribution.Under this condition,a significant amount of dislocation accumulation,dislocation bypassing,and dislocation tangling phenomena were observed in the SGY2 alloy.The primary deformation mechanism of unDRXed grains in the SGY2 alloy at the 420℃-ER9.4 may involve prismatic plane,pyramidal plane,and pyramidal plane<c+a>slip,thereby activating a significant amount of dislocations.Compared to other extrusion conditions,this condition is more prone to activate non-basal plane slip.The as-extruded SGY2 alloy exhibited superior mechanical properties,with ultimate tensile strength(UTS)and yield strength(YS)of 332 MPa and 278 MPa,respectively.This is mainly attributed to the extremely fine grains,with many DRXed grains having grain sizes smaller than 1μm,and higher density grain boundaries produced under this condition.Additionally,the unDRXed grains contain a high density of dislocations with small Schmid factor(SF),thus effectively inhibiting basal plane slip and strengthening the alloy to some extent.Similarly,the increased presence of second phase particles will also contribute to strengthening the alloy matrix through precipitation hardening.展开更多
A high-strength magnesium alloy containing Yb was prepared through a simple hot extrusion process.The effect of Yb addition on dynamic precipitation,texture evolution,dynamic recrystallization mechanisms,deformation m...A high-strength magnesium alloy containing Yb was prepared through a simple hot extrusion process.The effect of Yb addition on dynamic precipitation,texture evolution,dynamic recrystallization mechanisms,deformation mechanisms,and strengthening mechanisms in as-extruded Mg-4 Sm-3 Gd(-2 Yb)-0.5 Zr(SGY0,SGY2)alloys was systematically investigated.The results indicated that the average grain size decreased from 4.17μm to 1.48μm with the addition of Yb.This extreme grain refinement greatly enhances the strength.The addition of Yb significantly facilitated the phase precipitation,but did not change the texture type.The non-dynamic recrystallized(un DRXed)grains exhibited a strong basal plane texture of<0110>parallel to the extrusion direction(ED),while the dynamic recrystallized(DRXed)grains showed a weaker rare earth texture,characterized by<1212>//ED.Moreover,the as-extruded SGY0 and SGY2 alloys predominantly undergo continuous dynamic recrystallization(CDRX),and some DRXed grains exhibit a discontinuous dynamic recrystallization mechanism(DDRX).In addition,the addition of Yb facilitates the activation of non-basal plane slip.The dislocation types in the as-extruded SGY0 and SGY2 alloys include(a),(c)and(c+a)dislocations.However,the SGY2 alloy exhibits a relatively high dislocation density,which contributes to the enhancement of the strength.Extreme grain refinement and the dispersion of nanoscale second-phase particles are key factors in increasing the strength.展开更多
Magnesium-gadolinium(Mg-Gd)-based alloys have excellent high-temperature properties and the addition of two heterogeneous rare earth(RE)elements may promote the formation of secondary phase for better-strengthened pro...Magnesium-gadolinium(Mg-Gd)-based alloys have excellent high-temperature properties and the addition of two heterogeneous rare earth(RE)elements may promote the formation of secondary phase for better-strengthened properties.Herein,novel Mg-7Gd-2Nd-0.5Zr(wt%)alloys were prepared by synergistic reaction induced by high-speed extrusion(EX)and short-time aging treatment(AT).The microstructures,textures,and mechanical properties of the resulting alloys were then comprehensively studied by various analytical methods.The result reveals that the as-cast Mg-7Gd-2Nd-0.5Zr(wt%)alloy is composed of a-Mg matrix and Mg5(Gd,Nd)phase with bony and continuous networks at grain boundaries.The microstructure presents coarse deformed grains and fine recrystallized grains after high-speed EX,and formation of typical(0001)||ED extruded fiber texture and[1211]RE texture is observed.The EX22 sample exhibits more Mg5(Gd,Nd)precipitated phases,fuller DRXed grains,and shorter peak aging times than the EX9 sample.After the AT at 250℃,the proportion of deformed grains decreases due to static recrystallization,which leads to a reduction in the average grain size and weakening of the texture intensity.Therefore,combined effect of all strengthening mechanisms aids in achieving balance of high-strength and high-elongation for Mg-7Gd-2Nd-0.5Zr(wt%)alloy.The values of yield strength(YS),ultimate tensile strength(UTS),and elongation(EL)of EX22-A sample at room temperature are found to be 292.5 MPa,350.6 MPa,and 24.3%,respectively.Overall,this study provides relevant experimental basis and theoretical guidance for the development of high-strength Mg-RE alloys,which are useful for future consideration.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52371108,52201119)Frontier Exploration Project of Longmen Laboratory,China(LMQYTSKT014).
文摘The effect of different extrusion parameters on the microstructure and mechanical properties of Mg-4Sm-3Gd-2Yb-0.5Zr(SGY2)alloy was investigated.It was observed that under different extrusion parameters,unDRXed grains of SGY2 alloy exhibited a pronounced basal plane texture,specifically<01.10>//ED,while the texture of DRXed grains was relatively dispersed.Under the condition of 420℃ and an extrusion ratio of 9.4(420℃-ER9.4),the basal plane texture intensity of unDRXed grains in SGY2 alloy was the highest.Furthermore,SGY2 alloy at different extrusion parameters exhibited recrystallization mechanisms mainly characterized by continuous dynamic recrystallization(CDRX),with some DRXed grains and deformed grains experiencing discontinuous dynamic recrystallization(DDRX).Additionally,at the 420℃-ER9.4,the second phase particles in the as-extruded SGY2 alloy were smaller in size and exhibited a dispersed distribution.Under this condition,a significant amount of dislocation accumulation,dislocation bypassing,and dislocation tangling phenomena were observed in the SGY2 alloy.The primary deformation mechanism of unDRXed grains in the SGY2 alloy at the 420℃-ER9.4 may involve prismatic plane,pyramidal plane,and pyramidal plane<c+a>slip,thereby activating a significant amount of dislocations.Compared to other extrusion conditions,this condition is more prone to activate non-basal plane slip.The as-extruded SGY2 alloy exhibited superior mechanical properties,with ultimate tensile strength(UTS)and yield strength(YS)of 332 MPa and 278 MPa,respectively.This is mainly attributed to the extremely fine grains,with many DRXed grains having grain sizes smaller than 1μm,and higher density grain boundaries produced under this condition.Additionally,the unDRXed grains contain a high density of dislocations with small Schmid factor(SF),thus effectively inhibiting basal plane slip and strengthening the alloy to some extent.Similarly,the increased presence of second phase particles will also contribute to strengthening the alloy matrix through precipitation hardening.
基金financially supported by the National Natural Science Foundation of China(No.52371108,52201119,52203295)Frontier Exploration Project of Longmen Laboratory,China(LMQYTSKT014)the Joint Fund of Henan Science and Technology R&D Plan of China(242103810056)。
文摘A high-strength magnesium alloy containing Yb was prepared through a simple hot extrusion process.The effect of Yb addition on dynamic precipitation,texture evolution,dynamic recrystallization mechanisms,deformation mechanisms,and strengthening mechanisms in as-extruded Mg-4 Sm-3 Gd(-2 Yb)-0.5 Zr(SGY0,SGY2)alloys was systematically investigated.The results indicated that the average grain size decreased from 4.17μm to 1.48μm with the addition of Yb.This extreme grain refinement greatly enhances the strength.The addition of Yb significantly facilitated the phase precipitation,but did not change the texture type.The non-dynamic recrystallized(un DRXed)grains exhibited a strong basal plane texture of<0110>parallel to the extrusion direction(ED),while the dynamic recrystallized(DRXed)grains showed a weaker rare earth texture,characterized by<1212>//ED.Moreover,the as-extruded SGY0 and SGY2 alloys predominantly undergo continuous dynamic recrystallization(CDRX),and some DRXed grains exhibit a discontinuous dynamic recrystallization mechanism(DDRX).In addition,the addition of Yb facilitates the activation of non-basal plane slip.The dislocation types in the as-extruded SGY0 and SGY2 alloys include(a),(c)and(c+a)dislocations.However,the SGY2 alloy exhibits a relatively high dislocation density,which contributes to the enhancement of the strength.Extreme grain refinement and the dispersion of nanoscale second-phase particles are key factors in increasing the strength.
基金Project supported by the Natural Science Foundation of Shanxi Province(20210302123135,202303021221143)Scientific and Technological Achievements Transformation Guidance Special Project of Shanxi Province(202104021301022,202204021301009)+1 种基金Central Government Guided Local Science and Technology Development Projects(YDZJSX20231B003,YDZJSX2021A010)National Natural Science Foundation of China(52374395)。
文摘Magnesium-gadolinium(Mg-Gd)-based alloys have excellent high-temperature properties and the addition of two heterogeneous rare earth(RE)elements may promote the formation of secondary phase for better-strengthened properties.Herein,novel Mg-7Gd-2Nd-0.5Zr(wt%)alloys were prepared by synergistic reaction induced by high-speed extrusion(EX)and short-time aging treatment(AT).The microstructures,textures,and mechanical properties of the resulting alloys were then comprehensively studied by various analytical methods.The result reveals that the as-cast Mg-7Gd-2Nd-0.5Zr(wt%)alloy is composed of a-Mg matrix and Mg5(Gd,Nd)phase with bony and continuous networks at grain boundaries.The microstructure presents coarse deformed grains and fine recrystallized grains after high-speed EX,and formation of typical(0001)||ED extruded fiber texture and[1211]RE texture is observed.The EX22 sample exhibits more Mg5(Gd,Nd)precipitated phases,fuller DRXed grains,and shorter peak aging times than the EX9 sample.After the AT at 250℃,the proportion of deformed grains decreases due to static recrystallization,which leads to a reduction in the average grain size and weakening of the texture intensity.Therefore,combined effect of all strengthening mechanisms aids in achieving balance of high-strength and high-elongation for Mg-7Gd-2Nd-0.5Zr(wt%)alloy.The values of yield strength(YS),ultimate tensile strength(UTS),and elongation(EL)of EX22-A sample at room temperature are found to be 292.5 MPa,350.6 MPa,and 24.3%,respectively.Overall,this study provides relevant experimental basis and theoretical guidance for the development of high-strength Mg-RE alloys,which are useful for future consideration.
