Influence of thermomechanical processing and heat treatment on microstructure, tensile properties and fracture toughness of Ti-1100-0.1B alloy

The effects of thermomechanical processing and heat treatment on the microstructure, tensile properties and fracture toughness of 0.1 wt.% boron modified Ti-1100 alloy (Ti-1100-0.1B) processed by vacuum arc melting was investigated at room temperature and compared with that of the base alloy. The tensile properties of the base alloy (Ti-1100) were significantly lower in the β-processed as compared to α−β-processed conditions whereas the tensile properties of boron modified alloy (Ti-1100-0.1B) were similar irrespective of whether it was α−β or β-processed. The B addition resulted in a higher strengthening in β-processed alloy as compared to α−β-processed alloy. The fracture toughness of Ti-1100-0.1B alloy was also found to be lower than that of the base Ti-1100 alloy irrespective of the processing conditions and solution treatment temperatures. Neither the solution treatment temperature nor the processing condition had a significant effect on the fracture toughness of the B modified Ti-1100-alloy whereas in the case of the base alloy, the fracture toughness was distinctly higher in the β processed condition for all the solution treatment temperatures. The results were explained on the basis of the effect of processing and heat treatment on the microstructure as well as the role of TiB whiskers in influencing the strengthening as well as fracture mechanisms in Ti-1100 alloy.