Microstructure, mechanical properties and work hardening behavior of SiCp/2024Al composite sheet

Abstract

SiCp/2024Al composite material was prepared by ultrasonic assisted semi-solid stirring casting process, and then the two-step hot deformation（extrusion and rolling）was carried out to obtain SiCp/2024Al composite sheet with a thickness of 1 mm, the influence of SiCp content on its microstructure and mechanical properties was investigated. The results show that the rolled 2024 aluminum alloy consists of banded grains and bulk CuAl2 phase. Due to the promotion effect of SiCp on the dynamic recrystallization nucleus of the Al matrix, the grain size of the 2024 aluminum matrix was significantly refined. With the increase of the volume fraction of SiCp, its macroscopic distribution becomes more uniform. The two-step deformation results in the fracture of SiCp and CuAl2 phases, the fracture degree increases with the increase of the volume fraction of SiCp. When the SiCp volume fraction is 15%, the SiCp size is reduced to about 4.9 μm. With the increase of the SiCp volume fraction, the yield strength gradually increases. When SiCp volume fraction is 10%, the comprehensive mechanical properties of SiCp/2024Al composite plate are the best, and its yield strength, ultimate tensile strength and elongation can reach 305, 490 MPa and 8% respectively. With the increase of SiCp volume fraction, the thermal expansion coefficient of SiCp/2024Al composite decreases and the elastic modulus increases, when the SiCp volume fraction is 15%, the elastic modulus can reach 96 GPa, which is 37.1% higher than the 2024 aluminum alloy.

Keywords

• metal matrix composites
• sicp
• thermal deformation
• elastic modulus
• mechanical properties