Effect of Heat Treatments on Phase Transformation and Tensile Properties in Cast Ti-47Al-2Cr-2Nb Alloy

摘要

Microstructural refinement by two steps heat treatment in Ti-47Al-2Cr-2Nb at.% alloy, with samples' dimension of ? 15 mm × 80 mm, is studied in this paper. A coarse fully lamellar microstructure can be refined to a near gamma (NG) one with a grain size of ～ 180 μm by one step heat treatment of 1150 ~(°) C for 12 h. The instability of initial structure plays an important role in the transformation. Some samples are subsequently treated at 1280 ~(°) C for 2 h, the NG structure is further converted to a new lamellar structure through α laths precipitated with different directions within each γ grain and room temperature tensile elongation of the alloy is reached to a value of 1.28% after two steps heat treatments.