Effects of CuSn₃₃ content on the microstructure and mechanical properties of Al/Cu bimetallic foams

Abstract

A new type of Al/Cu bimetallic foams with double grade plateau stresses was prepared by employing powder metallurgy sintering method. The addition of CuSn33 is to improve the microstructure and mechanical properties of Al/Cu bimetallic foams. The effects of CuSn33 content on the phase components, lattice parameter, crystallize size and microstrain of Cu-matrix were investigated with utilizing Rietveld method. Results show that there is a linera relationship between CuSn33 content and lattice parameter, and the linear fitting equation was also simulated. The addition of CuSn33 can refine the crystallite and increase the microstrain when the Sn with larger atomic radius dissolves into Cu-matrix alloy. However, the microstrain value drops dramatically when the precipitated δ-phase appears from the supersaturated solute elements. Segregation caused by the residual Sn in the Cu-matrix primarily appears near to the border of Al2Cu and Cu-matrix. The compressive stress-strain curves of Al/Cu bimetallic foams with 5 typical stages are radically different from the single component metal foams, including twice quasi-linear regions, twice collapse plateaus, and the densification region. The effects of CuSn33 content on the elastic modulus of Al/Cu bimetallic foams, microhardness of Cu-matrix and the absorbed energy density have also been investigated.