GRAIN-SIZE REFINEMENT OF GAMMA-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 grai n sizes ranging from 320 nm to 7 mu m. Both the yield stress and tough ness Values have been confirmed to obey a Hall-Fetch dependence on gra in size, and at the same time, intergranular crack propagation and fai lure was observed. The very high strengths achieved in the materials h ave been correlated to the fine scale of the gamma-matrix and the tran sfer of slip across adjacent grains. (C) 1997 Elsevier Science S.A.