High-temperature mechanical properties of B2 type IrAl intermetallic compounds doped with Ni

Compression tests have been conducted to examine the mechanical behavior of polycrystalline Ir 1-x Ni x Al intermetallic compounds with x=0 to 0.8 at elevated temperatures. The crystal structure of the Ir 1-x Ni X Al compounds has been determined to be a B2 type ordered structure by X-ray analyses. Although IrAl fractures without exhibiting appreciable yielding at temperatures up to 873 K, a steady state-like deformation in IrAl takes place at temperatures higher than approximately 1273 K. Ductility of Ir 1-x Ni x Al is improved with increasing x. on the contrary, the strength decreases with increasing x in the intermediate temperature range. The IrAl alloy exhibits the 0.2% flow stress of 1200 MPa at 1073 K and 350 MPa at 1473 K, having the negative temperature dependence of the strength. Further more, the specific strength of Ir 1-x Ni x Al is almost independent of x at temperatures higher than approximately 1473 K. The 0.2% flow stress and the specific 0.2% flow stress of Ir 0.2 Ni 0.8 Al is significantly higher than that of binary NiAl over the entire temperature range to 1673 K.