Powder metallurgical processing of Ti6Al4V alloy

Ti6Al4V powders were produced by Argon gas atomization, the powder fraction < 250 mu m was hot isostatically pressed (HIP) at 920 degrees C and 140MPa. The properties of pre-alloyed powders and the compact were investigated in this paper. Powder particles are almost perfectly spherical. The microstructure of powder surface is approximate hexagonal cellular structure, the inner structure exhibits cellular alpha phase and needle-like martensite alpha' phase, these are resulting from the rapid solidification. After HIP, Ti6Al4V alloy has a Widmanstaten microstructure consisting of continuous grain boundary alpha (GB alpha) phase and beta transformation structure, the grain size of GB alpha phase is in the range of 5 similar to 15 mu m. The tensile test at room temperature shows that strength of samples is 880MPa, the fracture surface exhibits obvious brittle cleavage fracture features including cleavage facets with river pattern and a few elongate dimples of different sizes and big voids at localized area.