Influence of MgO whisker addition on microstructures and mechanical properties of WC-MgO composite

Abstract

WC-MgO whisker composite (abbreviated as WC-MgOw composites) has been sintered by hot pressing. The purpose of present study is to investigate the influence of various content of MgO whisker addition on mechanical performance of WC-MgOw composites. Vickers hardness and fracture toughness of WC-MgOw composites first increase and then decrease with the addition of MgO whisker. The optimal values of Vickers hardness and fracture toughness are achieved, respectively 20.92 GPa and 9.85 MPa m1/2, when the MgO whiskers content reaches 1 wt%. The fracture toughness of WC-MgOw composite is about higher 10.2% than the sample's without MgO whiskers. However, the relative density of the WC-MgOw composites decreases continuously with the addition of MgO whiskers. When the content of MgO whisker is relatively high, the fracture mode is changed and large pores appear. Thus, the mechanical properties of WC-MgOw composite is decreased. The main toughening mechanisms can attribute to crack deflection, crack bridging and whisker pull-out. The mixture of intergranular and transgranular fracture mode also increase the fracture toughness.