Achieving ultrafine grained and homogeneous AA1050/ZnO nanocomposite with well-developed high angle grain boundaries through accumulative press bonding

Abstract

Aluminum matrix nanocomposites with 2vol% ZnO nanoparticles were produced using accumulative press bonding (APB) as a very effective and novel severe plastic deformation process. Microstructural evaluation and mechanical properties of specimens were characterized by field-emission scanning electron microscopy (FE-SEM), scanning transmission electron microscopy (STEM), electron backscatter diffraction (EBSD) and tensile test. Microstructure of AA1050/ZnO nanocomposite showed a uniform distribution of ZnO nanoparticles throughout the aluminum matrix. STEM and EBSD observations revealed that ultrafine-grained Al/ZnO nanocomposite with the average grain size of <500nm and well-developed high angle grain boundaries (80% high angle boundaries and 37° average misorientation angle) was successfully obtained by performing 14 cycles of the APB process. When the number of APB cycles increased the tensile strength of Al/ZnO nanocomposite improved and reached 228MPa after 14 cycles, which was 2.6 and 1.3 times greater than the obtained values for annealed (raw material, 88MPa) and monolithic aluminum (180MPa), respectively.