Microstructure, mechanical property and oxidation property in Ni3Si-Ni3Ti-Ni3Nb multi-phase intermetallic alloys

Microstructure, high-temperature compressive and tensile deformation. and oxidation property of multi-pliase intermetallic alloys, which were based on the Ni3Si-Ni3Ti-Ni3Nb pseudo-temary alloy system and composed of L1(2), D0(24) and D0(4) phases, were investigated. The microstructures of these multi-phase intermetallic alloys were largely dependent on alloy composition, The Widmansttaten-like Ni3Ti(D0(24)) phase was precipitated from l, matrix by a solid-state reaction, accompanied with a certain orientation relationship and habit plane. The tensile stress as well as the tensile elongation of these multi-phase alloys increased with increasing Si content, i,e, the volume fraction of L1(2) phase in the wide range of test temperatures. Fifty parts per million boron addition to these multi-phase intermetallic alloys resulted in increased tensile stress and tensile elongation. It was found that the multi-phase intermetallic alloy with it high Si content had good oxidation resistance, accompanied with a continuous silicate layer. From an overall evaluation of the properties examined. it was shown that the multiphase intermetallic alloy that had a high Si content and was composed of L1(2) matrix dispersed by D0(21) and D0(4) phases had the most favorable properties as high-temperature mechanical and chemical materials. (c) 2005 Elsevier B.V. All rights reserved.