Mg-1Zn-1Gd合金在等径角挤压下的晶粒细化机理及织构演变

Grain Refinement and Texture Evolution of Mg-1Zn-1Gd Alloy in Equal Channel Angular Pressing

研究等径角挤压(ECAP)对Mg-1Zn-1GD合金组织、织构和动态再结晶行为的影响。结果表明,在350℃等径角挤压后,试样的显微组织由细小的再结晶晶粒组成,基体中有大量均匀分布的等轴晶。8道次后获得平均晶粒尺寸为3.6μm的均匀超细晶粒结构。不连续动态再结晶(DDRX)和连续动态再结晶(CDRX)导致晶粒细化。利用电子背散射衍射(EBSD)技术对织构进行了分析,发现经过4道次ECAP后,形成了较强的基面织构(多重随机分布~19.76)。随着挤压道次的增加,挤压合金板材基面上的晶粒主要沿挤压方向拉长,取向分布由集中状态向分散状态转变。织构减弱,最大值为15.66,且织构与Mg-1Zn-1GD合金的平面各向异性有关。

The effect of equal channel angular pressing(ECAP)on the microstructure and texture,as well as dynamic recrystallization behavior of Mg-1 Zn-1 Gd alloy(wt%)was investigated.The results show that after the equal channel angular pressing at 350℃,the microstructures of these samples are composed of fine recrystallized grains,and there are a large number of homogeneously distributed equiaxed grains in the matrix.Upon 8 passes,the uniform ultra-fine grain structure with an average grain size of 3.6μm is obtained.The mechanism of the discontinuous dynamic recrystallization(DDRX)and continuous dynamic recrystallization(CDRX)leads to grain refinement.The micro texture was analyzed through electron backscatter diffraction(EBSD)technique.It is revealed that after 4 passes of ECAP,a strong basal texture is achieved(multiple random distribution^19.76).With increasing the extrusion passes,the grain on the basal planes of extruded alloy sheet is mainly elongated along the extrusion direction,the orientation distribution changes from concentrated state to decentralized state.The texture is weakened and the maximum is 15.66.Finally,the texture is related to the plane anisotropy of the Mg-1 Zn-1 Gd alloy.