Effects of annealing on microstructures of V-4Cr-4Ti alloy

The alloy samples of V-4%Cr-4%Ti (V-4Cr-4Ti) alloy were annealed at 1000~1400°C, 1×10-2 Pa at different times (1 h or 3 h). The behaviour of dislocation, stacking fault and twin of alloy before/after anneal was analysed using transmission electron microscopy (TEM). The results showed that the dislocation density was very high in as-melt alloy with a small amount of stacking fault and twin. After annealing, the density of dislocation decreased but stacking fault and extended dislocation increased. The number of twin increased with the increase of anneals temperature and time. In the alloy annealed at 1200°C, the stacking fault paralleled to each other and resulted in the diffraction point of vanadium split, and the twin plane was the {211} plane of vanadium. The microstructure of alloy annealed at 1300°C/3 h was consisted of high-density twin and dislocation, which was named as "martensite-like" structure. In order to understand the evolvement of microstructure before and after high-temperature annealing. © Right.