Experimental approach to probe into mechanisms of high‐temperature erosion of NbB 2 ‐ZrO 2

In the backdrop of potential applications of boride‐based materials in high‐speed supersonic aircrafts, the present investigation probes in comprehending the mechanisms of high‐temperature erosive wear of spark plasma sintered NbB 2 ‐ZrO 2 composite. The solid particle erosion experiments were performed at different temperatures starting from room temperature (25°C) to 800°C using Al 2 O 3 particles (50 μm). The air‐erodent particle mixture was impinged toward the target surface at normal impact with a velocity of 50 m/s. The detailed microstructural analysis using HRTEM reveals the generation and accumulation of a large number of dislocations within NbB 2 and ZrO 2 grains of the eroded surfaces. Such observations indicate the activation of dislocation plasticity during erosion at 800°C. XRD‐based analyses provided residual stress‐based interpretation for the enhancement of erosion resistance at high temperatures. In contrast, substantial material loss via brittle failure, involving the generation and intersection of the lateral/radial cracks, was recorded after room temperature erosion. In case of erosion at 400°C and 800°C, the residual stress relaxes as a consequence of high‐temperature exposure prior to erosion. The accumulation of dislocations near the crater region and shot peening phenomena play a dominant role in decreasing erosion rate with increasing erosion test temperature.