ROOM-TEMPERATURE DEFORMATION-BEHAVIOR OF MULTIPHASE NI-20AT-PERCENT-AL-30AT-PERCENT-FE AND ITS CONSTITUENT PHASES

The microstructure of the multiphase alloy Ni-20Al-30Fe (where the composition is in approximate atomic per cent), processed through a casting and hot-extrusion route, consisted of a pro-eutectic beta' (ordered b.c.c. or B2-structured) phase in a fine (0.5-mu-m lamellae width) eutectic. The eutectic consisted of beta' + gamma (f.c.c.) phases; the gamma-phase itself contained gamma' (ordered f.c.c. or L1(2)-structured) precipitates. When tested in tension at room temperature, this alloy exhibited up to 20% elongation and a yield strength of up to 850 MPa. Crack stopping by the gamma-gamma' phase was concluded to be an important factor contributing to the ductility of the alloy. In contrast, beta' Ni-30Al-20Fe, which had a composition similar to that of the pro-eutectic phase of the multiphase alloy, exhibited a similar yield stress of 800 MPa but only 2% elongation. This alloy deformed by < 001 > slip. Finally, the alloy Ni-12Al-40Fe, which was similar to the gamma-gamma' phases of the multiphase alloy, exhibited 28% tensile elongation and a yield strength of 507 MPa and deformed by < 110 > slip.