Microstructure and mechanical properties of hot-pressed WC–MgO composites with Cr3C2 or VC addition

• Published in: International journal of refractory metals & hard materials 2013-11, Vol.41, p.41-47
• Main Authors: Ouyang, Chenxin, Zhu, Shigen, Dong, Weiwei, Qu, Haixia
• Format: Article
• Language: English
• Subjects: Grain growth inhibitors; Magnesium oxide; Sintering; Tungsten carbide
• ISSN: 0263-4368; 2213-3917
• DOI: 10.1016/j.ijrmhm.2013.01.015

The influence of Cr3C2 and VC addition on the microstructure and mechanical properties of WC–MgO composites hot-pressed at 1650°C for 90min was comprehensively investigated. The grain growth of WC was significantly retarded and the homogeneity of MgO particulate dispersion was effectively improved with the addition of 0.5wt.% Cr3C2 or 0.5wt.% VC. The indentation size effect (ISE) on hardness was restrained and the load-independent hardness was increased by doping grain growth inhibitors. Improvements on fracture toughness of hot-pressed samples were also observed due to the refined WC grains and uniformly dispersed MgO particulates. In addition, experimental results demonstrated that Niihara's equation was preferable for estimating the indentation fracture toughness, by comparing the fracture toughness evaluated using the single-edge V-notch beam (SEVNB) method with the values estimated through the Vickers indentation technique. ► VC or Cr3C2 addition improved the mechanical properties of WC–MgO composites. ► Indentation size effect was observed in the hardness measurement of WC–MgO composites. ► The load-independent hardness of WC–MgO composites was firstly calculated. ► Niihara's model was preferable for estimating the indentation fracture toughness.