Aging characteristics and precipitate analysis of Cu-Ni-Mn-P alloy

A copper-rich Cu-Ni-Mn-P alloy was designed to have high strength along with good electrical conductivity. Mechanical properties and electrical conductivities of three different Cu-Ni-Mn-P alloys and of the Cu-0.89%Ni-0.22%P and Cu-1.11 %Mn-0.28%P alloys were measured as a function of aging time at 723 K. The aging characteristics of the Cu-Ni-Mn-P alloys showed that the optimum combination of mechanical and electrical properties was obtained at a Ni:Mn:P molar ratio of about 1: 1: 1. The optimized Cu-Ni-Mn-P alloy showed better mechanical and electrical properties than the Cu-Ni-P and Cu-Mn-P alloys. The structure of precipitates in the optimized alloy was analyzed by transmission electron microscopy. The precipitates of the Cu-Ni-Mn-P alloy were identified to have a composition of MnNiP. The precipitate particle consists of the hexagonal MnNiP phase (C22 type) with the orthorhombic MnNiP platelets (C23 type). The {1 0 (1) over bar 0}(h) planes and (0 0 0 1)(h) directions of the hexagonal phase are parallel to the {0 0 1}(o) planes and (0 1 0)(o) directions of the orthogonal platelets, respectively. (c) 2006 Elsevier B.V. All rights reserved.