Effect of Solutes on Phase Stability in A13 Nb

Abstract

ABSTRACTAlloying transition metal trialuminides such as Al3Nb with appropriate ternary elements may stabilize the ordered cubic Ll2 structure relative to the DO22 structure. This may enhance the symmetry related contributions to plastic flow, thereby aiding in overcoming the low ductility in the trialuminide systems. The present investigation was directed towards exploring the potential for obtaining new ternary Al3Nb-based intermetallics with the Ll2 structure. The effects of various ternary elements on the phase stability of A13Nb were studied by SEM, XRD, and EPMA. Results of the A13 Nb-X phase relationship studies are presented. Preliminary microhardness results on the ternary DO22 Al3Nb-X phases are also reported. The predictive capabilities of Pettifor's structural stability scheme are evaluated in the light of the present investigation.