Microstructure evolution and deformation mechanisms of β phase in TiBw/Ti60 composites studied by reconstructing grain during the hot deformation

Abstract

Hot compression tests were performed on the TiBw/Ti60 composite in the single β phase region to study the microstructure evolution and deformation mechanisms. The stress-strain curves exhibited obvious flow softening above the strain rate of 0.01 s−1. While the stress-strain curves exhibited dynamic balance at strain rate of 0.001 s−1. Based on the analysis of EBSD data, method have been proposed to deduce the information of microstructure of prior β grains. The pole figures of recalculated β grains matched very well with the pole figures of selected α variants according to BOR. At low strain rate the elongated β grains can be reconstructed due to DRV. The results of reconstructing grains at different strain show that the deformation mechanism of TiBw/Ti60 composite is mainly dominated by DDRX at high strain rates in β phase region. Full equiaxed prior β grains can be observed at 1120 °C/0.1 s−1 and strain of 0.4. In addition, TiBw is beneficial to DRX of β grains due to the dislocation accumulation and providing the nucleation sites. These understanding can be applied to the relationship of microstructure evolution and thermal processing parameters in TiBw/Ti60 composite.