Consolidation of mechanically alloyed powder mixture of Cu–Zn alloy and graphite

Abstract

A powder mixture consisting of Cu–29.7at.% Zn alloy and graphite was mechanically alloyed in a planetary ball mill. The supersaturated solid solubility of carbon in the Cu–29.7at.% Zn alloy was determined to be 38.5at.% C (alloy composition: Cu–18.3at.% Zn–38.5at.% C) by the change in lattice parameter of the alloy. Supersaturated Cu–24.2at.% Zn–18.5at.% C alloy powder consolidated by a static compression stress of 1.4 GPa was found to have a relative density of 89.7%, a Vickers hardness of 147.2, and a compressive strength of 1.4 GPa which is equal to the statically consolidated compression stress. Moreover, the supersaturated solid-soluble carbon did not precipitate. When dynamically consolidated by a 93 g projectile at a speed of 38.1 m s −1 (estimated impact compression stress of 2.3 GPa) after static precompression of 0.4 GPa, the alloy powder was found to have a relative density of 93%, a Vickers hardness of 177, and a compressive strength of 2.3 GPa which is equal to the impact compression stress. Supersaturated solid solubility of 18.5at.% C decreased to 15at.% C after impact consolidation. The mechanically alloyed powders can maintain supersaturated solid solubility when consolidated by impact pressure, and especially when consolidated by static pressure.