Beneficial influence of copper and manganese alloying elements on the mechanical properties of metallic composite materials based on the eutectic Al-5.7% Ni alloy

Abstract

We have developed a new type of metallic composite material based on the binary eutectic Al-5.7 wt% Ni alloy. The structure of the initial alloys prepared by simple casting consists of strong, fine fibres of the Al₃Ni phase and a ductile aluminium matrix. These alloys are then transformed into dispersion-hardened materials by isostatic extrusion in which the Al₃Ni fibres are broken and dispersed in the ductile matrix. The materials thus prepared present a mechanical strength of the same order as the unidirectionally solidifed eutectic alloy: the tensile strength is nearly 300 MPa at room temperature. We observed in this work that the mechanical strength is remarkably increased by the addition of a small amount of copper or manganese: it attains about 400 MPa by the addition of 2 to 3wt% Cu, and more than 500 MPa by the addition of 3wt% Mn. These alloying elements also produce beneficial effects on the mechanical properties at high temperature.