Evaluation of NiAl and NiAl-B deposited by vacuum plasma spray

Abstract

Nickel aluminide, NiAl, has potential for high-temperature structural applications because of its high melting temperature, low density, high elastic modulus, and excellent oxidation resistance. However, inadequate room-temperature ductility and low strength at high temperatures limit the use of NiAl for practical service. An added limitation is the difficulty of forming this intermetallic compound. Plasma spray forming is suggested to produce NiAl in useful shapes and forms. In this study, vacuum plasma spray has been used to produce coatings and free-standing forms of NiAl and NiAl microalloyed with boron (NiAI-B). This research focuses on an investigation of the structures and properties of the as-sprayed deposits. Preliminary analysis reveals that the deposits formed by vacuum plasma spray are very dense and essentially oxide free. The as-received aluminide powders and the sprayed deposits have the same phase structure. Tests also indicate that the mechanical properties achieved by plasma spray are comparable to those achieved by other processing techniques.