Pop-in characteristic induced by nanoindentation in ZrB2-SiC composites

Abstract

In this research, instrumented nanoindentation tests were performed to determine the mechanical properties associated with pop-in events of the ZrB2-SiC composites reinforced with and without the mixture of boron nitride nanotubes (BNNTs) and boron nitride nanoplatelets (BNNPs). The results show the sintered ZrB2-SiC and (BNNTBNNP)/(ZrB2-SiC) composites have typical pop-in event, and the added mixture of BNNTs-BNNPs increases the critical load at pop-in, initial penetration depth and pop-in excursion at pop-in event. Moreover, the computed shear strength at which pop-in occurs increases with the mixture of BNNTs-BNNPs, which might be ascribed to Orowan-type strengthening effect. The indentation stress-strain curves of these ZrB2-SiC composites were also reconstructed. This research is expected to facilitate a better understanding of the microscopic plastic deformation behavior of ZrB2 and its composites. Keywords—ceramic matrix composites; boron nitride nanotubes; toughness; spark plasma sintering