Abstract
The effect of trace Al, V, Sn and Si addition on the grain refinement, hardness, and lattice strain was discussed. From the results of variation in the average grain size, it was found that the growth restriction factor of individual additions is Si>Al>Sn>V in order of their magnitude. The c⁄a ratio of other Ti alloys except for the Ti-Si alloy were the same value of 1.587 as pure Ti, whereas that of the Ti-Si alloy was 1.581, the lattice strain of which affected the hardness increase. It was then suggested that Si addition to pure Ti plays an important role in the hardness increase, which can be explained by the lattice strain caused by c⁄a ratio reduction, the decrease in the grain size of Ti-Si alloy, and the formation of Ti silicide at higher Si content.
