Open AccessEffect of Mo content on microstructure and mechanical properties of WCoB-TiC based cermets
Author(s) -
Kan Zheng,
Yong Zheng,
Fangfang Sun,
G T Zhang,
J J Zhang,
Xiangyu Xu,
Hao Wu,
Zhaoxia Dong,
Wei Zhou
Publication year - 2020
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/770/1/012058
Subject(s) - cermet , microstructure , materials science , scanning electron microscope , rockwell scale , porosity , sintering , fracture toughness , grain size , wetting , phase (matter) , composite material , toughness , metallurgy , ceramic , chemistry , organic chemistry
The effect of Mo content on microstructure and mechanical properties of WCoB-TiC based cermets fabricated by boronizing sintering reaction was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). Results showed that phase compositions of all the WCoB-TiC cermets with 0 to 20 wt% Mo addition were composed of W 2 CoB 2 , TiC, TiB 2 , and the (211) diffraction peak of W 2 CoB 2 phase was continuously shifted towards a high angle with Mo content, indicating that (W, Mo) 2 CoB 2 solid solutions in cermets with 5-20 wt% were formed. Moreover, the cores of W 2 CoB 2 grains were enriched in Mo, while rims of W 2 CoB 2 grains had a relatively lower Mo content, resulting in the formation of a core/rim structure. As Mo content increased, the porosity gradually dropped, while the relative density continuously increased, due to the improved wettability of liquid phase in the hard phase. In addition, average grain sizes dropped initially and then rose gradually with Mo content. An increase in average grain sizes was due to the coalescence and growth of hard-phase particles. The WCoB-TiC cermet with an 10 wt% Mo addition showed excellent comprehensive mechanical properties with a transverse rupture strength of 815 MPa, a Rockwell hardness of 93.4 HRA, and a fracture toughness of 12.5 MPam 1/2 , respectively.