Method to procuce fine-grained lamellar microstructures in gamma titanium aluminides

摘要

A method for producing fine-grained lamellar microstructures in powder metallurgy (P/M) and wrought gamma titanium aluminides comprises the steps of: (a) a cyclic heat treatment at a maximum temperature in the range of about 10° C. above to about 10° C. below the alpha- transus temperature (T.sub.&agr;) of the alloy, and (b) a secondary heat treatment of thus cyclically heat treated alloy at a temperature between 750° C. and 1050° C. for 4 to 100 hours. For cast gamma alloys, the method comprises additionally the step of a solution treatment at a temperature in the range of about 30° C. to 70. degree. C. above T.sub.&agr; followed by a water or an oil quench before the two steps described above. The alloys with the resulting fine- grained lamellar microstructure have an advantageous combination of mechanical properties--tensile strength, ductility, fracture toughness, and creep resistance.