Distribution of microscale stress and effect on mechanical performance of cermets with metallic nanoparticles in ceramic grains

This study realized modulation of size and content of metallic nanoparticles inside ceramic grains of cermets using WC-Co cemented carbides as an example. The approach was based on tailoring the composition of the in-situ reactants of synthesizing ceramic-metal composite powders. With the optimized size and content of nanoparticles distributing in WC grains, simultaneous improvement in hardness, strength, and fracture toughness was achieved in the prepared WC-Co cemented carbides, and the integrated mechanical properties reached the highest among the cermets with similar compositions reported in the literature. The effect of metallic nanophases in ceramic grains on the microscale stress and strain distributions of the cermets was quantitatively investigated. Detailed characterization and analysis of the interactions between the metallic nanophases and ceramic dislocations revealed that these nanophases hindered dislocation motion but did not cause local stress concentration and microcrack nucleation, hence enabled to concurrently strengthen and toughen the ceramic grains. This study provides a unique method and quantitative guideline for developing cermets with superior integrated mechanical properties, particularly important for cermet materials with low metal contents.