Indirect Extrusion of Tial-Based Intermetallics From Elemental Powders Metallurgy

Powder metallurgy has been successfully adopted in synthesizing intermetallic compounds based on TiAl. Indirect hot extrusion of elemental powder mixtures resulted in rods of about 2cm in diameter with the compositions based on Ti-46.6Al-1.4Mn-2Mo-0.3C (−0.33Y) (all in at.%). Among the processing parameters, degassing scheme, heating rate, extrusion can, die design, extrusion temperature and extrusion ratio were found to be crucial to ensure the sound mechanical properties at both room temperature and high temperatures. Further improvement in the mechanical properties was obtained by modifying the chemical composition with C and Y, which were effective in refining the microstructure, thus enhancing the tensile strength and plastic elongation at elevated temperature.