FORMATION OF TERNARY L12 COMPOUNDS IN AL3TI-BASE ALLOYS

Sintering of elemental powders was carried out to form ternary intermetallic compounds in Al-Ti-X systems. It was confirmed that L1(2) ternary compounds are formed in Al3Ti-base alloys containing Cr, Mn, Fe, Co, Ni, Cu, Zn, Rh, Pd, Ag, Pt, and Au. In some ternary systems, the L1(2) phase field and equilibrium phases surrounding the L1(2) phase at 1273 K or 1423 K have been established. Button ingots of some ternary L1(2) compounds were prepared by arc-melting to investigate their microstructure and bend ductility. In general, homogenization of as arc-melted button ingots substantially reduces the amount of second phases but introduces extensive porosity. However, no residual porosity was observed in higher Cr content alloys: Ti25Cr13Al62, Ti25Cr14Al61, and Ti25Cr16Al59. For Ti25Cr14Al61 alloy, a bend ductility as large as 0.9% was recorded at ambient temperature.