A Practical Method to Improve Mechanical and Electrical Properties of Ads Copper Prepared by Cold Spray Additive Manufacturing Through Powder Pretreatment

Abstract

To reduce the oxygen content on the surface of alumina dispersion-strengthened copper alloy powders, and improve properties of the deposits prepared by cold spray additive manufacturing, these powders were pretreated with hydrogen reduction treatment at 300 ℃ and 500 ℃, respectively. The microstructure and mechanical and electrical properties of the deposits before and after powder heat treatment were systematically researched. The results show that hydrogen reduction treatment can effectively reduce the oxide film on the surface of the alumina-dispersion-strengthened copper powder without changing the microstructure and mechanical properties of the powder. The alumina-dispersion-strengthened copper alloy deposit prepared from the as-received powder has obvious pores, and the tensile strength and electrical conductivity are 75 MPa and 38% IACS, while the deposits prepared from the powder treated at 300 ℃ and 500 ℃ present a dense microstructure. The tensile strengths and electrical conductivity are 200 MPa, 45%IACS and 245 MPa, 48% IACS, respectively. At the same time, the nano-Al2O3 particles are very stable under the heating and deformation conditions of adiabatic shearing by cold spraying, and the Al2O3 particles are not significantly broken during the severe plastic deformation caused by the high-speed impact of cold spraying, which enables the deposits to directly inherit the nano-dispersion strengthening structure of the powder. Therefore, it is effective to improve the mechanical and electrical properties of alumina dispersion-strengthened copper deposits by using hydrogen reduction pre-treatment to reduce the oxide film on the surfaces of the particles.

Keywords: Cold spray additive manufacturing, Alumina dispersion-strengthened copper, Heat treatment, Mechanical properties, electrical conductivity