针对商用镁合金板材难成形问题,探索将双辊铸轧(Twin roll casting,TRC)应用到含长周期有序结构相(Long period stacking ordered,LPSO)的Mg-Y-Zn(WZ)合金的可行性。构建二维简化模型并采用有限元软件模拟了不同LPSO相含量合金的TRC过...针对商用镁合金板材难成形问题,探索将双辊铸轧(Twin roll casting,TRC)应用到含长周期有序结构相(Long period stacking ordered,LPSO)的Mg-Y-Zn(WZ)合金的可行性。构建二维简化模型并采用有限元软件模拟了不同LPSO相含量合金的TRC过程。运用单因素分析和正交试验极差分析了冷却条件、轧辊转速和喷嘴温度等参数对铸轧成形性的影响。结果表明,随着Y含量增加,WZ合金凝固区间宽化,偏析倾向增大。影响WZ合金铸轧成形工艺因素由大到小依次为轧辊转速、LPSO相含量和喷嘴温度。同时,LPSO相与喷嘴温度的交互作用最为显著。随LPSO相含量增加,变形抗力提高,铸轧板材边裂严重,心部等效应变分布不均现象加剧,进一步导致开裂倾向增大。展开更多
The homogenized Mg−5.6Gd−0.8Zn(wt.%)alloys were treated with water cooling and furnace cooling to obtain specimens without and with the 14H long-period stacking ordered(LPSO)phase.Subsequently,multi-directional forgin...The homogenized Mg−5.6Gd−0.8Zn(wt.%)alloys were treated with water cooling and furnace cooling to obtain specimens without and with the 14H long-period stacking ordered(LPSO)phase.Subsequently,multi-directional forging(MDF)experiments were carried out.The microstructure and mechanical properties of different regions(the center,middle and edge regions)in the MDFed alloys were systematically investigated,and the effect of LPSO phase on them was discussed.The results show that the alloys in different regions undergo significant grain refinement during the MDF process.Inhomogeneous microstructures with different degrees of dynamic recrystallization(DRX)are formed,resulting in microhardness heterogeneity.The alloy with the LPSO phase has higher microstructure homogeneity,a higher degree of recrystallization,and better comprehensive mechanical properties than the alloy without the LPSO phase.The furnace-cooled alloy after 18 passes of MDF has the best comprehensive mechanical properties,with an ultimate compressive strength of 488 MPa,yield strength of 258 MPa,and fracture strain of 21.2%.DRX behavior is closely related to the LPSO phase and deformation temperature.The kinked LPSO phase can act as a potential nucleation site for DRX grains,while the fragmented LPSO phase promotes DRX nucleation through the particle-stimulated nucleation mechanism.展开更多
Rare-earth(RE) magnesium alloys have attracted lots of attention due to their excellent mechanical properties.In this work,the microstructure and mechanical properties of as-extruded 8.5Gd-4.5Y-0.8Zn-0.4Zr magnesium a...Rare-earth(RE) magnesium alloys have attracted lots of attention due to their excellent mechanical properties.In this work,the microstructure and mechanical properties of as-extruded 8.5Gd-4.5Y-0.8Zn-0.4Zr magnesium alloy under different solution treatment were examined with the optical microscope(OM),scanning electron microscope(SEM),high resolution transmission electron microscope(HRTEM),electron back-scattered diffraction(EBSD) and Instron testing machine.The results show that the ES12alloy(solution treatment for 12 h at 520℃) has the highest ultimate tensile strength(UTS) of 390 MPa with a fracture elongation of 24.5% at the co st of a minor drop in yielding strength(YS) compared to the asextruded alloy.During solution treatment,the block-shaped long period stacking ordered(LPSO) in asextruded alloy evolves into plate-shaped LPSO,which disperses at grain boundaries(GBs),and lamellar LPSO,which distributes in grains.The coexistence of plate-shaped and lamellar LPSO,which impedes the dislocations movement,and the activated dislocations are regarded as the primary reasons for mechanical properties improvement.Furthermore,the(11-21) <1-100> texture in as-extruded alloy transforms into the(11-20) <0001> texture in ES12 alloy.The average grain size increases from 3.45 μm in as-extruded alloy to 18.70 μm in ES12 alloy.The Schmid factors of {0001} <11-20>,{10-10} <11-20>,{10-11} <11-20>,and {11-22} <11-23> increase,which indicate that slip systems are more easily activated in plastic deformation.The dynamic recrystallization(DRX) grains fraction increase to 92.8% for ES12 alloy due to the particle-stimulated nucleation(PSN) mechanism triggered by block-shaped and plate-shaped LPSO.The freshly DRXed grains further weaken the texture,and reduce the dislocation density.All of these factors increase elongation of RE magnesium alloy.展开更多
The effects of the co-addition of Ni and Zn on the microstructure and mechanical properties of the extruded Mg-6.84Y2.45Cu(MYC,wt%)alloy were researched.Results show that the as-cast Mg-6.79Y-1.21Cu-1.12Ni-1.25Zn(MYCN...The effects of the co-addition of Ni and Zn on the microstructure and mechanical properties of the extruded Mg-6.84Y2.45Cu(MYC,wt%)alloy were researched.Results show that the as-cast Mg-6.79Y-1.21Cu-1.12Ni-1.25Zn(MYCNZ,wt%)alloy consists of theα-Mg,a few Y-rich phases,lamellar 18R-long period stacking ordered(LPSO)phase,and granular Mg_(2)(Cu,Ni,Zn)phase.After the homogenization process,phase transformation occurs in MYCNZ alloy.Some 18R-LPSO phases at the grain boundary are transformed into the thin striped 14H-LPSO phase in the grains.After extrusion,the amount,morphology,and distribution of the second phase are changed,and the grain size of the extruded MYCNZ alloy is significantly reduced to approximately 2.62µm.Additionally,a weaker basal texture is formed in the extruded MYCNZ alloy.The tensile results indicate that the co-addition of Ni and Zn significantly enhances the tensile strength of the extruded MYC alloy while maintaining good ductility.The tensile yield strength(σ_(0.2)),ultimate tensile strength(σ_(b)),and elongation to failure(ε_(L))of the extruded MYCNZ alloy are 266.9 MPa,299.8 MPa,and 20.1%,respectively.This alloy has a good strength-plastic synergistic effect.The excellent tensile strength of the extruded MYCNZ alloy at room temperature is mainly due to grain refinement and the second phase strengthening effect,and its outstanding ductility is ascribed to the texture weakening and activation of non-basal slips.展开更多
The LPSO phase can effectively enhance the mechanical properties of Mg alloys.To investigate the impact of different LPSO phase contents and morphologies on the mechanical properties and strengthening mechanisms of Mg...The LPSO phase can effectively enhance the mechanical properties of Mg alloys.To investigate the impact of different LPSO phase contents and morphologies on the mechanical properties and strengthening mechanisms of Mg-Y-Al alloys under room temperature deformation,this study prepared Mg-12Y-1Al(WA121)alloys containing Bulk-LPSO(B-LPSO),Lattice-LPSO(L-LPSO),and Needle-like LPSO(N-LPSO)with different contents through different heat-treatment processes.The results indicate that with the increase in heat treatment time,the contents of B-LPSO phases remain essentially unchanged,and the contents of L-LPSO and N-LPSO phases gradually increase.The increase in N-LPSO phase content is the most pronounced,with the highest content(7.29%)observed in the alloy treated for 4.5 h.Moreover,the alloy treated for 4.5 h exhibits the best mechanical properties,with ultimate tensile strength(UTS),tensile yield strength(TYS),and elongation(EL)values of 177 MPa,139 MPa,and 4.27%,respectively.Compared to the as-cast alloy,UTS,TYS,and EL increased by 9.94%,11.2%,and 27.1%,respectively.The study reveals that all three LPSO phases exhibit excellent dislocation hindering effects,effectively enhancing strength of the alloy.Additionally,the N-LPSO phase,due to its dense distribution,forms numerous dislocation channels within the grains,dispersing stress concentration within the grains to improve plasticity of the alloy.Furthermore,the interaction between the N-LPSO phase and the other phases in the alloy can also enhance plasticity of the alloy.Therefore,the alloy treated for 4.5 h demonstrates a synergistic improvement in strength and plasticity.Research has revealed that the precipitation mechanism of the N-LPSO phase in the as-cast WA121 alloy involves the formation of an Al-rich region adjacent to the needle-like Mg_(24)Y_(5) phase.Subsequently,the Y element provided by the dissolving Mg_(24)Y_(5) phase reacts with this region,ultimately leading to the formation of the needle-like LPSO phase.展开更多
文摘针对商用镁合金板材难成形问题,探索将双辊铸轧(Twin roll casting,TRC)应用到含长周期有序结构相(Long period stacking ordered,LPSO)的Mg-Y-Zn(WZ)合金的可行性。构建二维简化模型并采用有限元软件模拟了不同LPSO相含量合金的TRC过程。运用单因素分析和正交试验极差分析了冷却条件、轧辊转速和喷嘴温度等参数对铸轧成形性的影响。结果表明,随着Y含量增加,WZ合金凝固区间宽化,偏析倾向增大。影响WZ合金铸轧成形工艺因素由大到小依次为轧辊转速、LPSO相含量和喷嘴温度。同时,LPSO相与喷嘴温度的交互作用最为显著。随LPSO相含量增加,变形抗力提高,铸轧板材边裂严重,心部等效应变分布不均现象加剧,进一步导致开裂倾向增大。
基金the financial supports from the Key Research and Development Program of Hunan Province,China(No.2023GK2020)。
文摘The homogenized Mg−5.6Gd−0.8Zn(wt.%)alloys were treated with water cooling and furnace cooling to obtain specimens without and with the 14H long-period stacking ordered(LPSO)phase.Subsequently,multi-directional forging(MDF)experiments were carried out.The microstructure and mechanical properties of different regions(the center,middle and edge regions)in the MDFed alloys were systematically investigated,and the effect of LPSO phase on them was discussed.The results show that the alloys in different regions undergo significant grain refinement during the MDF process.Inhomogeneous microstructures with different degrees of dynamic recrystallization(DRX)are formed,resulting in microhardness heterogeneity.The alloy with the LPSO phase has higher microstructure homogeneity,a higher degree of recrystallization,and better comprehensive mechanical properties than the alloy without the LPSO phase.The furnace-cooled alloy after 18 passes of MDF has the best comprehensive mechanical properties,with an ultimate compressive strength of 488 MPa,yield strength of 258 MPa,and fracture strain of 21.2%.DRX behavior is closely related to the LPSO phase and deformation temperature.The kinked LPSO phase can act as a potential nucleation site for DRX grains,while the fragmented LPSO phase promotes DRX nucleation through the particle-stimulated nucleation mechanism.
基金supported by the Key Research and Development Program of Heilongjiang (2022ZX01A01)National Natural Science Foundation of China (51975167)Natural Science Foundation of Heilongjiang Province(LH2022E080)。
文摘Rare-earth(RE) magnesium alloys have attracted lots of attention due to their excellent mechanical properties.In this work,the microstructure and mechanical properties of as-extruded 8.5Gd-4.5Y-0.8Zn-0.4Zr magnesium alloy under different solution treatment were examined with the optical microscope(OM),scanning electron microscope(SEM),high resolution transmission electron microscope(HRTEM),electron back-scattered diffraction(EBSD) and Instron testing machine.The results show that the ES12alloy(solution treatment for 12 h at 520℃) has the highest ultimate tensile strength(UTS) of 390 MPa with a fracture elongation of 24.5% at the co st of a minor drop in yielding strength(YS) compared to the asextruded alloy.During solution treatment,the block-shaped long period stacking ordered(LPSO) in asextruded alloy evolves into plate-shaped LPSO,which disperses at grain boundaries(GBs),and lamellar LPSO,which distributes in grains.The coexistence of plate-shaped and lamellar LPSO,which impedes the dislocations movement,and the activated dislocations are regarded as the primary reasons for mechanical properties improvement.Furthermore,the(11-21) <1-100> texture in as-extruded alloy transforms into the(11-20) <0001> texture in ES12 alloy.The average grain size increases from 3.45 μm in as-extruded alloy to 18.70 μm in ES12 alloy.The Schmid factors of {0001} <11-20>,{10-10} <11-20>,{10-11} <11-20>,and {11-22} <11-23> increase,which indicate that slip systems are more easily activated in plastic deformation.The dynamic recrystallization(DRX) grains fraction increase to 92.8% for ES12 alloy due to the particle-stimulated nucleation(PSN) mechanism triggered by block-shaped and plate-shaped LPSO.The freshly DRXed grains further weaken the texture,and reduce the dislocation density.All of these factors increase elongation of RE magnesium alloy.
基金Major Science and Technology Project of Gansu Province(22ZD6GA008)National Natural Science Foundation of China(52261027,51961021,52001152)+2 种基金Open Project of State Key Laboratory for Mechanical Behavior of Materials(20192102)Undergraduate Innovation and Entrepreneurship Training Program(DC20231188,DC20231482,DC20231558,DC20231469,DC20231441)Supported by Sinoma Institute of Materials Research(Guang Zhou)Co.,Ltd(SIMR)。
文摘The effects of the co-addition of Ni and Zn on the microstructure and mechanical properties of the extruded Mg-6.84Y2.45Cu(MYC,wt%)alloy were researched.Results show that the as-cast Mg-6.79Y-1.21Cu-1.12Ni-1.25Zn(MYCNZ,wt%)alloy consists of theα-Mg,a few Y-rich phases,lamellar 18R-long period stacking ordered(LPSO)phase,and granular Mg_(2)(Cu,Ni,Zn)phase.After the homogenization process,phase transformation occurs in MYCNZ alloy.Some 18R-LPSO phases at the grain boundary are transformed into the thin striped 14H-LPSO phase in the grains.After extrusion,the amount,morphology,and distribution of the second phase are changed,and the grain size of the extruded MYCNZ alloy is significantly reduced to approximately 2.62µm.Additionally,a weaker basal texture is formed in the extruded MYCNZ alloy.The tensile results indicate that the co-addition of Ni and Zn significantly enhances the tensile strength of the extruded MYC alloy while maintaining good ductility.The tensile yield strength(σ_(0.2)),ultimate tensile strength(σ_(b)),and elongation to failure(ε_(L))of the extruded MYCNZ alloy are 266.9 MPa,299.8 MPa,and 20.1%,respectively.This alloy has a good strength-plastic synergistic effect.The excellent tensile strength of the extruded MYCNZ alloy at room temperature is mainly due to grain refinement and the second phase strengthening effect,and its outstanding ductility is ascribed to the texture weakening and activation of non-basal slips.
基金supported by the Qinghai Provincial Science and Technology Department Basic Research Program(No.2025ZY029).
文摘The LPSO phase can effectively enhance the mechanical properties of Mg alloys.To investigate the impact of different LPSO phase contents and morphologies on the mechanical properties and strengthening mechanisms of Mg-Y-Al alloys under room temperature deformation,this study prepared Mg-12Y-1Al(WA121)alloys containing Bulk-LPSO(B-LPSO),Lattice-LPSO(L-LPSO),and Needle-like LPSO(N-LPSO)with different contents through different heat-treatment processes.The results indicate that with the increase in heat treatment time,the contents of B-LPSO phases remain essentially unchanged,and the contents of L-LPSO and N-LPSO phases gradually increase.The increase in N-LPSO phase content is the most pronounced,with the highest content(7.29%)observed in the alloy treated for 4.5 h.Moreover,the alloy treated for 4.5 h exhibits the best mechanical properties,with ultimate tensile strength(UTS),tensile yield strength(TYS),and elongation(EL)values of 177 MPa,139 MPa,and 4.27%,respectively.Compared to the as-cast alloy,UTS,TYS,and EL increased by 9.94%,11.2%,and 27.1%,respectively.The study reveals that all three LPSO phases exhibit excellent dislocation hindering effects,effectively enhancing strength of the alloy.Additionally,the N-LPSO phase,due to its dense distribution,forms numerous dislocation channels within the grains,dispersing stress concentration within the grains to improve plasticity of the alloy.Furthermore,the interaction between the N-LPSO phase and the other phases in the alloy can also enhance plasticity of the alloy.Therefore,the alloy treated for 4.5 h demonstrates a synergistic improvement in strength and plasticity.Research has revealed that the precipitation mechanism of the N-LPSO phase in the as-cast WA121 alloy involves the formation of an Al-rich region adjacent to the needle-like Mg_(24)Y_(5) phase.Subsequently,the Y element provided by the dissolving Mg_(24)Y_(5) phase reacts with this region,ultimately leading to the formation of the needle-like LPSO phase.
