Wetting of Low Carbon Steel by High-Entropy Melts CuSnBiPbGa, CuSnBiPbIn and CuSnBiInCd and Formed Structure of Diffusion Layers

Abstract

We present a result of a study of reactive wetting of surface of low carbon steel by liquid alloys CuSnBiPbGa, CuSnBiPbIn and CuSnBiInCd of equiatomic composition. Dependences of contact angle and spot diameter of wetted surface on temperature and time were studied. Liquid alloy CuSnBiPbGa begins wetting of surface of steel at 900 °C; spreading rate at higher temperatures increased by 8 times. Liquid alloy CuSnBiPbIn begins wetting surface of steel at 780°C, but spreading speed is almost unchanged with the further increase in temperature. Liquid alloy CuSnBiInCd begins wetting of surface of steel at a temperature of 570°C, and spreading is in a flash in nature. We studied microstructure and chemical composition of diffusion layers, formed at the spreading of liquid alloys of equiatomic composition CuSnBiPbGa, CuSnBiPbIn and CuSnBiInCd on steel surface. In all experiments at boundary with substrate a ductile transition layer of a solid solution of iron-based is formed. The thickness of diffusion layer side depends on the alloy composition. The widest diffusion layers formed for alloy CuSnBiInCd, and the most narrow - for alloy CuSnBiPbGa. We detected in segregations of copper and gallium atoms for bimetallic sample "CuSnBiPbGa+steel", of copper and tin atoms for samples "CuSnBiPbIn+steel" and "CuSnBiInCd+steel" in diffusion layers. The results of these studies have significance for the design of soldering technology and application of protective coatings on steel products.