Wu Guoqin, Yu Jianmin, Jia Leichen, Xu Wenlong, Dong Beibei, Zhang Zhimin, Hao Biying
School of Material Science and Engineering, North University of China, Taiyuan 030051, China.
Xi'an Modern Chemistry Research Institute, Xi'an 710065, China.
Materials (Basel). 2020 Nov 3;13(21):4932. doi: 10.3390/ma13214932.
Reciprocating Upsetting-Extrusion (RUE) deformation process can significantly refine the grains size and weaken the basal plane texture by applying a large cumulative strain to the alloy, which is of great significance to weaken the anisotropy of magnesium (Mg) alloys and increase the application range. In this paper, the Mg-8.27Gd-3.18Y-0.43Zr (wt %) alloy was subjected to isothermal multi-passes RUE. The microstructure and texture evolution, crystal orientation-dependent deformation mechanism of the alloy after deformation were investigated. The results clearly show that with the increase of RUE process, the grains are significantly refined through continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) mechanisms, the uniformity of the microstructure is improved, and the texture intensity is reduced. At the same time, a large number of particle phases are dynamically precipitated during the deformation process, promoting grain refinement by the particle-stimulated nucleation (PSN) mechanism. The typical [10-10] fiber texture is produced after one pass due to the basal plane of the deformed grains with a relatively high proportion is gradually parallel to the ED during extrusion process. However, the texture concentration is reduced compared with the traditional extrusion deformation, indicating that the upsetting deformation has a certain delay effect on the subsequent extrusion texture generation. After three or four passes deformation, the grain orientation is randomized due to the continuous progress of the dynamic recrystallization process.
往复镦粗-挤压（RUE）变形工艺通过对合金施加较大的累积应变，能够显著细化晶粒尺寸并弱化基面织构，这对于削弱镁（Mg）合金的各向异性及扩大其应用范围具有重要意义。本文对Mg-8.27Gd-3.18Y-0.43Zr（wt%）合金进行了等温多道次RUE加工。研究了该合金变形后的微观组织与织构演变、晶体取向相关的变形机制。结果表明，随着RUE加工道次的增加，通过连续动态再结晶（CDRX）和不连续动态再结晶（DDRX）机制，晶粒显著细化，微观组织均匀性提高，织构强度降低。同时，在变形过程中大量颗粒相动态析出，通过颗粒激发形核（PSN）机制促进晶粒细化。由于在挤压过程中，具有较高比例的变形晶粒基面逐渐平行于挤压方向（ED），一道次加工后会产生典型的[10-10]纤维织构。然而，与传统挤压变形相比，织构集中程度降低，表明镦粗变形对后续挤压织构的产生具有一定的延迟作用。经过三道次或四道次变形后，由于动态再结晶过程的持续进行，晶粒取向随机化。
