Effects of network-distributed TiB on dynamic recrystallization of TiB/(TA15-Si) composites during the deformation in β phase region

Abstract. To study the effects of network distributed TiB on dynamic recrystallization of high temperature β phase of near α titanium matrix composites, the TiB/(TA15-Si) composites were compressed under 1000℃ with strain rates ranging from 1 s-1~0.01 s-1. Results show that the flow stress was sensitive to strain rates. During hot compression, the microstructure evolution included single TiB rotation, network structure changing from circular to oval, and dynamic recrystallization (DRX) of high temperature β phase. The mechanism of DRX was continuous and discontinuous DRX mixed mechanism. Attributed to the accelerative effects of TiB by providing nucleation sites and improving storage energy, DRX preferentially occurred around TiB. After compression, equiaxed grains of high temperature β phase were formed in TiB rich region, while elongated grains were formed in TiB lean region. The dislocations density in elongated grains at higher strain rate was higher than that at lower strain rate. Under high strain rate, high temperature β phase was dominated by DRX in TiB rich region and dynamic recovery in TiB lean region. Under lower strain rates, high temperature β phase was dominated by the growth of DRX grains.