Mechanical responses, texture and microstructural evolution ofhigh purity aluminum deformed by equal channel angular pressing

WANG Bing-feng(汪冰峰)^{1, 2, 3}, SUN Jie-ying(孙杰英)¹, ZOU Jin-dian(邹金佃)¹, VINCENT Sherman², LI Juan(李娟)¹

(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Departments of Mechanical and Aerospace Engineering and Nanoengineering,
University of California, San Diego CA 92093-0411, USA;
3. Key Lab of Nonferrous Materials of Ministry of Education (Central South University), Changsha 410083, China)

Abstract:Ultra？ne-grained (UFG) high purity aluminum exhibits a variety of attractive mechanical properties and special deformation behavior. Equal channel angular pressing (ECAP) process can be used to easily and effectively refine metals. The microstructure and microtexture evolutions and grain boundary characteristics of the high purity aluminum (99.998%) processed by ECAP at room temperature are investigated by means of TEM and EBSD. The results indicate that the shear deformation resistance increases with repeated EACP passes, and equiaxed grains with an average size of 0.9 μm in diameter are formed after five passes. Although the orientations distribution of grains tends to evolve toward random orientations, and microtextures (80°, 35°, 0°), (40°, 75°, 45°) and (0°, 85°, 45°) peak in the sample after five passes. The grain boundaries in UFG aluminum are high-angle geometrically necessary boundaries. It is suggested that the continuous dynamic recrystallization is responsible for the formation of ultrafine grains in high purity aluminum. Microstructure evolution in the high purity aluminum during ECAP is proposed.

Key words:equal channel angular processing (ECAP); aluminum; grain refinement; microstructure; mechanical property