No abstract

No abstract

No abstract

Ti 2 AlNb-based alloys are synthesized by spark plasma sintering from prealloyed and ball-milled Ti-22Al-25Nb powder, and the structure of the alloys is regulated by aging at 800 C for 0.5, 1, 2, and 3 h. Comparison of phase composition, microstructure, and mechanical properties are made in this study. Aging in the B2 þ O phase region refers to the reversible transformation of B2 $ O. Complete B2 þ O Widmanstätten structure is obtained in the aged alloys synthesized from pre-alloyed powder, and the ones from milled powder contain acicular O and B2 þ O Widmanstätten structure. Ball milling eliminates the B2 þ O colonies, facilitates the continuous transformation of O ! B2, and induces acicular O in the alloys; however, the hardness of these alloys is decreased in contrast with that of the ones synthesized from prealloyed powder. Owing to the precipitation strengthening based on a large amount of fine O-phase precipitates, the 3 h aged alloy from pre-alloyed powder exhibits comprehensive mechanical properties with Vickers hardness of 448 AE 9 HV, ultimate tensile strength of 730 MPa, and elongation of 0.43%.