Microstructure Evolution of Ti-35V-15Cr-Si-C during Annealing Treatment

Microstructures morphology and phases of Ti-35V-15Cr-xSi-yC alloy during different annealing and solution treatments were studied using OM, XRD, SEM and TEM. The results indicate that the amount of small grains in grain-boundary increases but their sizes change slightly for the specimen annealed below 900 degrees C. The microstructure morphology shows small differences for different annealed specimens below 900 degrees C. When the annealing temperature is above 900 degrees C, the small grains at grain-boundary grow obviously and the microstructure morphology changes visibly. There are four precipitations in the alloy microstructure, i.e. spherical particle precipitation of Ti2C, "chicken feet" type precipitation of (TiV)C, dot particle precipitation of Ti5Si3 and needle-like precipitation of alpha. The solvus temperature for precipitation of (TiV)C and Ti5Si3 in Ti-35V-15Cr-xSi-yC is in temperature range from 950 to 1000 degrees C and 1000 to 1050 degrees C, respectively. When the solution temperature increases to 1200 degrees C, there is only partial solution of Ti2C.