Nanostructure evolution of reticular nano-TiB whiskers reinforced titanium matrix composite subjected to ultrasonic shot peening

Abstract

Titanium matrix composites (TMCs) have drawn widespread attention because of their superior mechanical properties. In this study, nano-TiB whiskers reinforced TMC was fabricated using a direct laser deposition technique and then subjected to ultrasonic shot peening (USP) for different durations. The microstructure characterization results indicated that the surface grain refinement of αTi was dominated by complicated dislocation motion. The primary grain refinement mode during the microstructure evolution was the transverse splitting of the elongated lamellae. By interacting with dislocations, the TiB whiskers facilitated the evolution of nanostructures. After USP treatment, TiBw exhibited obvious fractures, but the TiB-Ti interface remained sharp and clear, showing excellent interfacial properties. The use of USP resulted in a significant compressive residual stress field, which increased with peening time. Surface hardness also increased as a result of fine grain and strain strengthening. When compared to the initial sample, the maximum microhardness of the sample after USP treatment increased by 48%.