镁合金AZ31高温形变机制的织构分析

Texture investigation on the deformation mechanisms in magnesium alloy AZ31 deformed at high temperatures

利用X射线衍射和背散射电子衍射方法测定了镁合金AZ31高温动态再结晶和超塑形变时的宏观和微观织构,分析了晶粒内部的形变机制.结果表明,在动态再结晶和超塑形变过程中,晶粒内部的滑移机制仍起重要作用,表现为再结晶晶粒出现择优取向以及一些晶粒可充分均匀形变成长条状.宏观织构的测定表明,具有不同初始织构的两类样品高温动态再结晶时,新晶粒有不同的取向择优过程,形成相似的织构;长条形变晶粒内部开动的滑移系也有一定的差异.分析了不同温度下相同的织构对应的不同塑变机理.取向成像分析表明,基面织构取向的晶粒间总伴随着较高比例的小角晶界和30°<0001>的取向关系,这是六方结构的六次对称性限制了动态再结晶时(亚)晶粒间取向差的有效增大的缘故.

Deformation mechanisms of a magnesium alloy AZ31 deformed at high temperature in the presence of dynamic recrystallization and super-plasticity were investigated by texture analysis using X-ray diffraction and electron back scattering diffraction techniques. The results show that deformation by plastic slip inside grains still plays an important role due to the facts that preferred orientations are found in recrystallized grains and some strongly elongated deformed grains are present in samples. Difference in texture can be detected in the new grains of samples with different initial textures, and different slip mechanisms are ascribed to the elongated deformed grains in different samples. The improved plasticity due to the increase of temperature in deformed grains with same orientation was discussed. Orientation mapping reveals a misorientation distribution of large amount of small angle grain boundaries and an orientation relationship of 30°(0001) among basal oriented grains which is due to the 6-fold crystallographic symmetry of hexagonal close-packed structure of magnesium.