Oxidation behaviors and structural evolution of titanium matrix composites with the addition of TiBw/nano-silicide

Abstract

The challenge of enhancing the high-temperature oxidation resistance of titanium alloys is hereby addressed by the addition of TiB whiskers and nano-silicide. The cyclic oxidation tests results showed that the weight gains of the composites with reinforcements were less than that of titanium alloy, and the oxidation film of the silicide/composite only appears little peeling after heating at 1123 K for 100 h. The grains were refined by the introduction of reinforcements, thus the high-density grain boundary can be also used as the nucleation site of oxidation products to refine the oxide grains and effectively inhibit the internal diffusion process of oxygen. Additionally, nano-silicide distribution at grain boundaries cause short-circuit diffusion, resulting in preferential oxidation at grain boundaries thus forming a network structure, which effectively hinders the inward diffusion of oxygen and better inhibits the growth of oxidation scale. DFT calculation shows that TiBw and nano silicide reinforcement with weak oxygen binding ability can reduce the adsorbed oxygen atoms and prevent the further oxidation growth of the matrix.