Insights into microstructural evolution and dissolution characteristics of reinforced particles in tungsten carbide‑nickel composite coatings prepared by laser hot-wire deposition

Abstract

Tungsten carbide‑nickel (WC-Ni) composite coatings were firstly prepared on martensite stainless steel 2Cr13 by laser hot-wire deposition. The microstructural evolution and the dissolution characteristics of ceramic particles in the coatings had been systematically investigated. The results showed that the tungsten carbides' dissolution and microstructures in the coatings were close related to the dilution degree of the base metal. Apart form large retained particles, the coating with a lower dilution ratio (8.4%) was composed of Ni, Ni/Ni3B eutectics, and in-situ W2C particles. The W2C phase was preferentially dissolved while the WC was retained in W2C/WC eutectoid-structured particles, which exhibited the typical thermal damage patterns including the dissolution-diffusion and partially/completely fragmentation-dissolution-diffusion. The amount of M6C carbides was increased with the increment of dilution ratio (from 9.5% to 24%), and the ceramic particles suffered from more severe heat damage which mainly exhibited the characteristics of dissolution-diffusion-precipitation. Not only was the W2C phase was dissolved, the WC phase was also decomposed and reacted into M6C carbides. Due to the reinforcement of retained particles and the precipitated carbides, these coatings showed higher hardness and wear resistance which was about 1.9– 2.3 and 12.1– 26.9 times that of 2Cr13 substrate.