Effect of synthetic Mo2FeB2 powder on the microstructure and mechanical properties of Mo2FeB2-based cermets

Abstract

In this study, synthetic Mo2FeB2 powder was utilized to fabricate Mo2FeB2-based cermets. The influence of Mo2FeB2 powder on phase composition, microstructure, interfacial characteristics and mechanical properties of cermets was systematically investigated. It was found that two distinct grains were formed in the microstructure due to the addition of Mo2FeB2 powder, namely matrix grains and core/rim grains. Among them, matrix grains were in-situ generated by reaction boronizing sintering and exhibited elongated shape, and the undissolved Mo2FeB2 particles formed equiaxed core/rim grains through the dissolution-precipitation mechanism. With increasing Mo2FeB2 content from 0 to 92.5 wt%, the number of core/rim grains gradually increased while matrix grains continued to decrease, and average grain size decreased from 2.51 to 1.16 μm. In addition, a coherent relationship was formed between (220)Grain and (110)Binder at the core/rim grains-binder interface, thus enhancing interfacial bonding strength. When Mo2FeB2 content reached 92.5 wt%, the hardness, strength and toughness of cermets were found to be 88.5 ± 0.2 HRA, 2203 ± 25 MPa and 21.8 ± 0.3 MPa·m1/2, respectively.