High Temperature Materials Based on the Intermetallic Compound NiAl Reinforced by Refractory Metals for Advanced Energy Conversion Technologies

Advanced NiAl-based high temperature materials are developed and characterized for structural applications in energy conversion systems. The intermetallic compound NiAl with B2 superlattice structure exhibits superior physical and high temperature mechanical properties, and excellent oxidation resistance. Disadvantages of polycrystalline pure NiAl are the lack in plasticity and fracture toughness at room temperature and insufficient high temperature strength at temperatures above 800 degrees C. The refractory metals Cr, Mo, and Re form with NiAl quasi-binary eutectic systems which enable to produce metal fibres reinforced NiAl-based alloys in the as-cast condition and by performing directional solidification. These in-situ composites show fine-grained and thermally stable microstructures possessing high temperature strength, superior creep resistance and sufficient room temperature ductility.