【摘要】 采用HOPKINSON压杆装置和帽形试样对工业纯钛TA2进行高速冲击,利用扫描电镜(SEM)、透射电镜(TEM)、和高分辨透射电镜(HREM)研究剪切带内部微观组织的演化过程。结果表明:剪切带内没发生相变,剪切带组织由细小的等轴晶组成,剪切带内的动态再结晶过程是通过晶粒机械碎化及晶界迁移、亚晶粗化的混合机制和渐进式亚晶位向差的再结晶机制共同作用完成。更多还原

【Abstract】 Microstructural evolution of the adiabatic shear bands originated by the deformation of high strain for TA2 has been examined. Tests were performed using a specially designed stepped specimens in a Hopkinson bar. Upon completion of deformation, the region is cooled below half the temperature achieved during adiabatic heating for less than one millisecond. Microsturctural characterizations of shear bands were analysed using SEM, TEM and the TEM of high resolving power. No evidence of transition from α-Ti to another phases within the adiabatic shear bands could be found. However, the kinetics of boundary refinement processes were not taken into account in these studies with the distinctive characteristic of recrystallized microstructure. It is shown that there is no phase transformation in the TA2 adiabatic shear bands, which are composed of fine equiaxed grains. The dynamic recrystallization in the TA2 adiabatic shear bands was performed by the mixed mechanism of grain mechanical fragmentation, grain boundary transfer and subgrain roughen, and the recrystallization mechanism of progressive subgrain misorientation.更多还原