Heterogeneous–Nano Structure and Mechanical Properties of Co–added Cu–Ni–Si Alloy

Abstract

The microstructure and mechanical and electrical properties of two kinds of high concentration Corson alloys, which contained different amounts of Co substitution in Ni, were systematically investigated. After 90％ cold rolling, a heterogeneous–nano (HN) structure, composed of “eye”–shaped twin domains, shear bands and conventional low–angle lamellae, was fully developed in both alloys. The substitution of Co increased the volume fraction of the twin domains. Moreover, pre–aging treatment of the alloys before the cold rolling further enhanced the volume fraction of the twin domains. The alloys with and without pre–aging treatment were subjected to principal aging at various temperatures after the cold rolling. The peak hardness and electrical conductivity increased by the effects of pre–aging. And the peak–aged Co–substituted alloys exhibited superior balance of mechanical/electrical properties than that in the alloy without Co substitution. Nevertheless, the difference in the amount of Co substitution did not significantly affect the properties since the solvus of the δ phase in the alloys were almost unchanged by the Co substitutions.