Grain-size refinement of γ-Ti-Al alloys: effect on mechanical properties

A series of Ti-Al alloys was prepared by consolidation of atomised and mechanically milled powders based on the composition Ti-48Al-2Mn-2Nb and containing carbon additions. The microstructures obtained had grain sizes ranging from 320 nm to 7 μm. Both the yield stress and toughness values have been confirmed to obey a Hall-Petch dependence on grain size, and at the same time, intergranular crack propagation and failure was observed. The very high strengths achieved in the materials have been correlated to the fine scale of the γ-matrix and the transfer of slip across adjacent grains.