Micromechanisms of damage in a hypereutectic Ti-6Al-4V-B alloy

Abstract

The tensile stress-strain response and fracture in a hypereutectic Ti-6Al-4V-1.7B (weight percent) alloy were investigated by employing interrupted tensile tests combined with acoustic emission measurements, with the aim to identify the cause for the observed low ductility in this alloy. These tests were complemented with microscopy. The alloy contains TiB whiskers of different length scales, the majority of which include micro-whiskers (~5-10 μ m length) and a few primary-whiskers (~200-300 μ m length). Although the fracture of both types of whiskers occur during deformation, the former leads to a gradual decrease in the secant modulus whereas initiation of the latter leads to a drastic drop in the modulus along with failure of the specimen, limiting the ductility.