Influence of Constrained High-Pressure Torsion on Microstructure and Mechanical Properties of an Aluminum-Based Metal Matrix Composite

Abstract

Multilayered Al-Cu composites were fabricated successfully by constrained high-pressure torsion (HPT) in a Bridgeman anvil type unit under an applied pressure of 6.0 GPa after ten turns. Due to the good strain compatibility of Al and Cu, achieved during HPT, separate discs bonded without pores and cracks. Microstructural characterization of the processed disks showed that the originally flat interface between Al and Cu layers transforms, and some bindings and vortice-like folding are formed in a submicron multilayered structure embedded in an Al-rich matrix in almost all volumes. This led to an exceptional increase of ultimate strength. The tensile tests showed the value of the tensile strength reached 485 MPa at room temperature, which is several times higher than in pure aluminum (80 MPa) and copper (190 MPa) subjected to the same processing. Such an increase in the ultimate strength is associated with hardening due to formation of a multiphase fine-grained structure. This study indicates a high potential for the application of high-pressure torsion in bonding of Al and Cu to produce composites with enhanced mechanical properties.