Study on the Microstructure and High-Temperature Oxidation Performance of β-NiAl/γ′-Ni3Al Intermetallic Compounds Fabricated by Laser Metal Deposition

Four Ni-Al intermetallic compounds with the Al concentrations in range of 28 to 35 (in atomic percentage) have been fabricated by laser metal deposition (LMD) through mixing appropriate contents pure Ni powder pre-alloyed high-Al nickel aluminide powder. Ni-35Al and Ni-32Al are both composed more than 45 vol.% β-NiAl matrix phase dispersing γ′-Ni3Al, while Ni-30Al Ni-28Al consisted worm-like, needle-like γ′-Ni3Al mainly less 37 β-NiAl. After 20 h oxidation air at 1000 °C, results thermobalance, X-ray diffraction scanning electron microcopy, indicated that oxidation-resistant Ni-28Al. Because first two can thermally grow an external Al2O3 scale but second form a duplex oxide consisting outer NiAl2O4 layer inner layer.