纯镁塑变机理及其组织特征

借助光学显微镜和透射电镜,研究热挤压变形比和冷却方式对纯镁塑性变形机理及其显微组织的影响。结果表明,随变形比的增大,晶粒逐渐细化,孪晶带的宽度变小并最终消失;热变形后的快速冷却抑制了静态再结晶的发生,使动态再结晶组织得以保留;380oC热挤并于室温下压缩变形5%后,在一次孪晶带内部出现大量的二次孪晶。孪晶是纯镁高温及室温变形的主要形变亚结构形式。

Mechanisms and microstructure of plastic deformation in pure magnesium

The influence of extrusion ratios and cooling rate on mechanisms and microstructure of plastic deformed pure magnesium was studied by optical microscopy and transmission electron microscopy (TEM). The results showed that with increasing the ratio, grain size gradually decreased, and twins became smaller and tended to disappear at last. After hot-extrusion, the rapid cooling might inhibit static recrystallization, and the microstructure of dynamic recrystallization could be retained. After hot-extruded at 380 ℃ and then compressed for 5% at room temperature, secondary twins appeared inside the primary twins. Moreover, twinning was a main deformation mechanism of pure magnesium at high temperature and room temperature.