Microstructural Control of Ti-Al-Mo-Nb Alloy System With Respect to Variation of B

In the current study, phase stability of Ti-Al-Mo-Nb alloys was investigated, and the effect of B addition was examined for cast alloys. The fabricated cast alloys were mainly composed of alpha(2) /gamma lamellar with a beta phase, when they were heat treated at 1100 degrees C followed by air cooling, the alloy was composed of alpha(2) /gamma lamellar with gamma+beta necklace phase at the colony boundary for the Ti-45Al-3Mo-2Nb-1B alloy, and the colony size was refined to similar to 20 mu m. In order to identify the effect of the microstructures on mechanical strength, compressive tests were performed on the fabricated alloys of Ti-45Al-3Mo-2Nb and Ti-45Al-3Mo-2Nb-1B at room temperature and at 800 degrees C. The microstructural variations and phase stability were discussed in terms of pseudo-binary phase diagram calculated by Pandat software (TM).