The static recrystallization and associated texture evolution were investigated in an extruded Mg-Zn-Gd alloy with bimodal microstructure based on a quasi-in-situ electron back-scatter diffraction(EBSD)method.The typi...The static recrystallization and associated texture evolution were investigated in an extruded Mg-Zn-Gd alloy with bimodal microstructure based on a quasi-in-situ electron back-scatter diffraction(EBSD)method.The typical rare earth(RE)texture formed during annealing,evolving from the bimodal microstructure with[1010]basal fiber texture that consisted of fine recrystallized(RXed)grains and coarse unrecrystallized(un RXed)grains elongated along the extrusion direction.In both RXed and un RXed regions,the RXed nucleation produced randomized orientations without preferred selection and the RXed grains with RE texture orientation had more intensive growth ability than those with basal fiber orientation,thereby leading to the preferred selection of RE texture orientation during grain growth.The relationships between stored strain energy,solute drag,grain growth and texture evolution are discussed in detail.This study provided direct evidence of the RE texture evolution in an extruded Mg-RE alloy,which assists in understanding the formation mechanisms for RE texture during extrusion and better developing wrought Mg alloys with improved formability.展开更多
Multi- and unidirectional impact forgings were successfully applied to a （GW94） Mg-RE alloy. The microstructure and texture evolution were investigated systematically. The obtained results indicated that during unid...Multi- and unidirectional impact forgings were successfully applied to a （GW94） Mg-RE alloy. The microstructure and texture evolution were investigated systematically. The obtained results indicated that during unidirectional impact forging, a bimodal chain deform microstructure was sustained till last forging pass, whereas { 10-12} extension twins-assisted continuous dynamic recrystallization took place during the multidirectional impact forging （MDIF）. The coalescence and intersection of {10-12} extension twins during MDIF efficiently refined the original coarse grains and led to an almost recrystallized homogeneous microstructure. The texture analysis demonstrated that unidirectional impact forging yielded out the strong basal texture; however, MDIF resulted in non-basal texture, which was attributed to the cooperative effects of continuous DRX, twinning, and MDIF itself during the deformation process.展开更多
Multi-directional impact forging(MDIF)was applied to a Mg-7Al-2Sn(wt.%)Mg alloy to investigate its effect on the microstructural evolution.MDIF process exhibited high grain refinement efficiency.After MDIF 200 passes,...Multi-directional impact forging(MDIF)was applied to a Mg-7Al-2Sn(wt.%)Mg alloy to investigate its effect on the microstructural evolution.MDIF process exhibited high grain refinement efficiency.After MDIF 200 passes,the grain size drastically decreased to 20µm from the initial coarse grains of~500µm due to dynamic recrystallization(DRX).Meanwhile,original grain boundaries remained during MDIF and large numbers of fine sphericalβ-Mg_(17)Al_(12) particles dynamically precipitated along the original grain boundaries with high Al concentration,acting as effective pinning obstacles for the suppression of DRXed grain growth.Besides,micro-cracks nucleated during MDIF and propagated along the interface between the remained globular or cubic Al-Mn particles and Mg matrix.展开更多
基金the financial supports from the National Natural Science Foundation of China(NSFC,No.52005340 and 51601193)State Key Program of National Natural Science of China(No.51531002)+3 种基金National Key Research and Development Program of China(No.2016YFB0301104)National Basic Research Program of China(973 Program,No.2013CB632202)Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110541)Shenzhen Bureau of Industry and Information Technology(No.ZDYBH201900000008)。
文摘The static recrystallization and associated texture evolution were investigated in an extruded Mg-Zn-Gd alloy with bimodal microstructure based on a quasi-in-situ electron back-scatter diffraction(EBSD)method.The typical rare earth(RE)texture formed during annealing,evolving from the bimodal microstructure with[1010]basal fiber texture that consisted of fine recrystallized(RXed)grains and coarse unrecrystallized(un RXed)grains elongated along the extrusion direction.In both RXed and un RXed regions,the RXed nucleation produced randomized orientations without preferred selection and the RXed grains with RE texture orientation had more intensive growth ability than those with basal fiber orientation,thereby leading to the preferred selection of RE texture orientation during grain growth.The relationships between stored strain energy,solute drag,grain growth and texture evolution are discussed in detail.This study provided direct evidence of the RE texture evolution in an extruded Mg-RE alloy,which assists in understanding the formation mechanisms for RE texture during extrusion and better developing wrought Mg alloys with improved formability.
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0301104)the National Natural Science Foundation of China(Nos.51531002,51301173 and 51601193)the National Basic Research Program of China(‘‘973 Program’’,No.2013CB632202)
文摘Multi- and unidirectional impact forgings were successfully applied to a （GW94） Mg-RE alloy. The microstructure and texture evolution were investigated systematically. The obtained results indicated that during unidirectional impact forging, a bimodal chain deform microstructure was sustained till last forging pass, whereas { 10-12} extension twins-assisted continuous dynamic recrystallization took place during the multidirectional impact forging （MDIF）. The coalescence and intersection of {10-12} extension twins during MDIF efficiently refined the original coarse grains and led to an almost recrystallized homogeneous microstructure. The texture analysis demonstrated that unidirectional impact forging yielded out the strong basal texture; however, MDIF resulted in non-basal texture, which was attributed to the cooperative effects of continuous DRX, twinning, and MDIF itself during the deformation process.
基金The authors gratefully acknowledge the financial support from General Motors Corporation,the National Basic Research Program of China(973 Program,No.2013CB632202)National Natural Science Foundation of China(NSFC,No.51301173).
文摘Multi-directional impact forging(MDIF)was applied to a Mg-7Al-2Sn(wt.%)Mg alloy to investigate its effect on the microstructural evolution.MDIF process exhibited high grain refinement efficiency.After MDIF 200 passes,the grain size drastically decreased to 20µm from the initial coarse grains of~500µm due to dynamic recrystallization(DRX).Meanwhile,original grain boundaries remained during MDIF and large numbers of fine sphericalβ-Mg_(17)Al_(12) particles dynamically precipitated along the original grain boundaries with high Al concentration,acting as effective pinning obstacles for the suppression of DRXed grain growth.Besides,micro-cracks nucleated during MDIF and propagated along the interface between the remained globular or cubic Al-Mn particles and Mg matrix.
