EVALUATION OF REFRACTORY INTERMETALLICS WITH A15 STRUCTURE FOR HIGH-TEMPERATURE STRUCTURAL APPLICATIONS

With the advent of ceramic superconductors, while interest in the A15 intermetallics such as Nb3Al is declining, their potential for high temperature structural applications appears promising. The A15 compounds, though considered to have the simplest of the topologically closed packed structures, form a distinct class of intermetallics with a cubic structure and are adjacent phases to the refractory metal solid solutions. This report summarizes the evaluation of microstructures, mechanical properties and cyclic oxidation resistance of Nb3Al and Cr3Si and their ternary alloys, and to a limited extent binary V3Si. The mechanical properties of binary compounds, elastic modulus, ultimate strength and creep behavior, are compared with known data for other A15 compounds. Solubility limits, melting point suppression and enhancement in creep resistance of several ternary alloys based on Nb3Al and Cr3Si are summarized. The mechanical properties and microstructural observations are discussed from the perspective of developing high temperature structural materials based on A15 intermetallics.