Synthesis and Compression Property of Oxidation-Resistant Ni–Al Foams

Abstract

Three different Ni–Al foams were synthesized by vapor aluminizing with control of aluminizing time. Oxidation tests under 1100 °C and compression tests were conducted to evaluate the oxidation resistance and compression properties of the foams. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) tests were carried out to study the phase composition and microstructure of Ni–Al foams before and after oxidation. Results showed that vapor aluminizing process did not change the foam macro- and microstructure, and the phase composition became from β/γ′-phase to single β-phase as the aluminizing time extending. The Ni–Al foams possessed excellent oxidation resistance, and decreased Al content increased oxidation weight gain and altered oxidation products. Foams containing single β-phase presented obvious brittleness under compression tests, but the foam with β/γ′-phase exhibited elasticity and toughness to a certain extent. The elasticity and toughness of the foams significantly can be improved after oxidation because of the phase changing in matrix during oxidation, and the pre-oxidized high-Al-content Ni–Al foams exhibited good compression properties, as well as excellent oxidation resistance.