The grain growth process plays an important role in the texture formation in magnesium alloys.The microstructural and micro-textural evolution of a cold-rolled Mg-Zn-Gd alloy during annealing at 350℃for 60-190 min we...The grain growth process plays an important role in the texture formation in magnesium alloys.The microstructural and micro-textural evolution of a cold-rolled Mg-Zn-Gd alloy during annealing at 350℃for 60-190 min were tracked by quasi-in-situ electron backscatter diffraction method.The results show that grain growth takes place gradually with the annealing time increasing.Moreover,the TD-split texture maintains the texture type but alters in three aspects-the increased tilting angle,the decreased pole intensity and the widened distribution of high-intensity area.Grains with their c-axis tilting 45-70°from normal direction show preferential growth which is closely associated with the texture changes.The original grain size advantage is one of the important factors leading to the growth advantage,some grain boundaries,such as 50-60°[1^(-)21^(-)0],50-60°[2750],60-70°[1^(-)21^(-)0](18b),and 70-80°[1^(-)01^(-)0](10)are also considered to be related to this preferential growth.展开更多
The static recrystallization process of a cold-rolled Mg-Zn-Gd alloy was tracked by a quasi-in-situ electron backscatter diffraction method to investigate the orientations of nuclei.The results show that orientation d...The static recrystallization process of a cold-rolled Mg-Zn-Gd alloy was tracked by a quasi-in-situ electron backscatter diffraction method to investigate the orientations of nuclei.The results show that orientation distribution of nuclei is associated with nucleation mechanism.The continuous static recrystallization nuclei display similar orientations to the parent grains with TD orientation.Differently,discontinuous static recrystallization nuclei formed within the parent grains(TD-45~0 orientation) show random orientations and a variety of misorientation angles but preferred axes <5273> or <5270>.Interestingly,a special oriented nucleation is found.Discontinuous static recrystallization nuclei originated from boundaries of the parent grain(TD-70° orientation) show concentrated TD orientations in another side due to the preferred misorientation relationship 70°<1120>(∑18 b).It is speculated that these two special misorientation relationships are related to the dislocation type.展开更多
Obviously planar anisotropy due to‘TD split’orthotropic texture(TD indicates Transverse direction)always exist in the Rare-earth(RE)or Ca containing Mg alloy sheets,which is likely caused by the lowreduction rolling...Obviously planar anisotropy due to‘TD split’orthotropic texture(TD indicates Transverse direction)always exist in the Rare-earth(RE)or Ca containing Mg alloy sheets,which is likely caused by the lowreduction rolling(and annealing)as revealed in our previous research.In this work,the as-cast billets of a ZWK100 alloy were subjected to final-pass heavy reduction rolling(FHRR)at 500°C with different reductions(30%-70%)after rough rolling,aiming to investigate the reduction effect on the microstructure and texture formation.The results show that FHRR with higher reductions above 50%is in favor of shear banding formation but has little effect on the as-deformed texture components,and the excellent formability with single-pass reduction up to 70%is mainly ascribed to the activation of prismatic slip.FHRR with reduction above 50%and annealing can generate uniform grain structures of~10μm and symmetrical‘oblique-line split’texture in(0001)pole figures,with basal poles tilting by about 50°from ND(Normal direction)towards some oblique-line of TD and RD(Rolling direction)as well as uniform distribution of counter lines as an annular shape,resulting in excellent elongation to failure of~50%and ultra-low planar anisotropyΔr_of~0.1 and high stretch formability(Erichsen value:8.1).The formation‘oblique-line split’texture in(0001)pole figures is mainly correlated with the preferred growth tendency of grains with■//RD,which was suggested to relate to the high mobility of some special boundaries such as 40°-45°■.The influences of starting textures on the mechanical properties,planar anisotropy and related deformation modes,as well as their correlations with the stretch formability were comparatively investigated with the‘TD split’orthotropic texture as a counterpoint.展开更多
基金financial supports from the National Natural Science Foundation of China(NSFC,No.51601193)State Key Program of National Natural Science of China(No.51531002)+1 种基金National Key Research and Development Program of China(No.2016YFB0301104)National Basic Research Program of China(973 Program,No.2013CB632202)。
文摘The grain growth process plays an important role in the texture formation in magnesium alloys.The microstructural and micro-textural evolution of a cold-rolled Mg-Zn-Gd alloy during annealing at 350℃for 60-190 min were tracked by quasi-in-situ electron backscatter diffraction method.The results show that grain growth takes place gradually with the annealing time increasing.Moreover,the TD-split texture maintains the texture type but alters in three aspects-the increased tilting angle,the decreased pole intensity and the widened distribution of high-intensity area.Grains with their c-axis tilting 45-70°from normal direction show preferential growth which is closely associated with the texture changes.The original grain size advantage is one of the important factors leading to the growth advantage,some grain boundaries,such as 50-60°[1^(-)21^(-)0],50-60°[2750],60-70°[1^(-)21^(-)0](18b),and 70-80°[1^(-)01^(-)0](10)are also considered to be related to this preferential growth.
基金the financial supports from the National Natural Science Foundation of China(NSFC,No.51601193)State Key Program of National Natural Science of China(No.51531002)+1 种基金National Key Research and Development Program of China(No.2016YFB0301104)National Basic Research Program of China(973 Program,No.2013CB632202)。
文摘The static recrystallization process of a cold-rolled Mg-Zn-Gd alloy was tracked by a quasi-in-situ electron backscatter diffraction method to investigate the orientations of nuclei.The results show that orientation distribution of nuclei is associated with nucleation mechanism.The continuous static recrystallization nuclei display similar orientations to the parent grains with TD orientation.Differently,discontinuous static recrystallization nuclei formed within the parent grains(TD-45~0 orientation) show random orientations and a variety of misorientation angles but preferred axes <5273> or <5270>.Interestingly,a special oriented nucleation is found.Discontinuous static recrystallization nuclei originated from boundaries of the parent grain(TD-70° orientation) show concentrated TD orientations in another side due to the preferred misorientation relationship 70°<1120>(∑18 b).It is speculated that these two special misorientation relationships are related to the dislocation type.
基金financially supported by Basic and Applied Basic Research Fund of Guangdong Province of China(No.2019A1515110573)National Natural Science Foundation of China(No.51901047)+2 种基金Special Innovation Projects of Universities in Guangdong Province(2018KTSCX240)Key Project of Department of Education of Guangdong Province(No.2016GCZX008)Project of Engineering Research Center of Foshan(No.20172010018)。
文摘Obviously planar anisotropy due to‘TD split’orthotropic texture(TD indicates Transverse direction)always exist in the Rare-earth(RE)or Ca containing Mg alloy sheets,which is likely caused by the lowreduction rolling(and annealing)as revealed in our previous research.In this work,the as-cast billets of a ZWK100 alloy were subjected to final-pass heavy reduction rolling(FHRR)at 500°C with different reductions(30%-70%)after rough rolling,aiming to investigate the reduction effect on the microstructure and texture formation.The results show that FHRR with higher reductions above 50%is in favor of shear banding formation but has little effect on the as-deformed texture components,and the excellent formability with single-pass reduction up to 70%is mainly ascribed to the activation of prismatic slip.FHRR with reduction above 50%and annealing can generate uniform grain structures of~10μm and symmetrical‘oblique-line split’texture in(0001)pole figures,with basal poles tilting by about 50°from ND(Normal direction)towards some oblique-line of TD and RD(Rolling direction)as well as uniform distribution of counter lines as an annular shape,resulting in excellent elongation to failure of~50%and ultra-low planar anisotropyΔr_of~0.1 and high stretch formability(Erichsen value:8.1).The formation‘oblique-line split’texture in(0001)pole figures is mainly correlated with the preferred growth tendency of grains with■//RD,which was suggested to relate to the high mobility of some special boundaries such as 40°-45°■.The influences of starting textures on the mechanical properties,planar anisotropy and related deformation modes,as well as their correlations with the stretch formability were comparatively investigated with the‘TD split’orthotropic texture as a counterpoint.