Abstract:
The b-solidifying g-TiAl intermetallic alloys of nominal composition Ti-48Al (binary alloy), Ti-48Al-2Nb
(ternary alloy), Ti-48Al-2Nb-0.7Cr (quaternary alloy), and Ti-48Al-2Nb-0.7Cr-0.3Si (quinary alloy) (in
at.%) were developed. The materials produced were tensile tested at room temperature. The as-cast
microstructures and fracture surfaces of the tensile tested specimens were examined using conventional
metallographic methods. Microstructural examination indicated that the alloys were comprised of
lamellar structures (a2+g) embedded in columnar dendritic cores in the as-cast condition. However, the
quinary alloy contained a Ti5Si3 second phase. The alloys exhibited no detectable ductility during tensile
deformation, indicating the brittleness of all the materials. The fracture surfaces revealed that the alloys
failed by translamellar fracture with correspondingly few cleavage facets.
