The interrupted hot compression of an as-forged titanium matrix composite: flow softening behavior and deformation mechanism

Abstract

In this paper, the deformation behavior and microstructure evolution of 2.5vol.% (TiBw + TiCp)-containing high-temperature titanium matrix composite (TMCs) was studied by the interrupted compression tests. The flow stress–strain curves of reloading of TMCs showed the flow softening behavior. The decrease of flow stress was associated with increasing holding time and deformation temperature or decreasing strain rate. The static softening mechanism was associated with the DRV, DRX and consume of dislocations during interrupted holding (SRV) reflected by the Q, n and microstructure. The fraction of αp phase decreased with increased holding time and deformation temperature or decreased strain rate. Due to the transformation of αp phase to β phase, the high-temperature deformation ability of the TMCs will be improved a lot, which is consistent with the decreased flow stress. For the reinforcements and αp phases, they played restricted role in the growth of α/β colonies. However, the decrease of αp phase made the grown up of α/β colonies in low strain rate. The deformation mechanism of the composites was cDRX caused by the transformation of LABs into HABs by progressive lattice rotation of α phase in (α+β) region and dDRX attributed to the nucleation and growth process of β grains in β region. Due to the addition of reinforcements, the weaken microtexture of composite can be obtained. After the interrupted compression, the optimal deformation parameter has been found for the TMCs, which can give guidance for the subsequent hot-working.