Formation of Cu–Pb alloys by means of liquid metal homogenization

Abstract

The microstructure of Cu–Pb alloys containing 7, 32, 50, 55, and 73 at % Pb, preliminarily over-heated in the liquid state to 1300°C and crystallized with a cooling rate of 10 K/s is investigated. It is shown that melt overheating leads to the complete or partial suppression of metal stratification and the formation of its more homogeneous structure, which indirectly evidences the variation in the structural state of metallic liquid. The application of the homogenizing thermal treatment of Cu–Pb melts by overheating to a temperature definite for each composition as the method for the formation of bulk ingots with a homogeneous structure is substantiated. It is shown that the Cu–50 at % Pb melt, which has the highest mixing enthalpy, is the most promising composition for the formation of bulk ingots by the homogenizing thermal treatment of the melt. The smallest difference in microhardness of the phases based on copper and lead for the Cu–50 at % Pb alloy determines the ability of the material to bear mechanical loads without residual shaping and destruction, as well as stability to various types of wear.