Preparing W-Ni3Al alloy at low sintering temperature by adding MoO3: Microstructure, mechanical properties, and salt spray corrosion

Abstract

Aiming at poor comprehensive properties and high sintering temperature in the reported W-Ni3Al alloys as well as considering its future application in the marine environment, the W-Ni3Al-MoO3 alloys with good mechanical properties and fine tungsten grain were sintered at a low temperature of 1200 °C, and then we comparatively investigated the salt spray corrosion properties of the W-10Ni3Al (0WNM) and W-8.5Ni3Al-1.5MoO3 (1.5WNM) alloys. The MoO3 reacted with Al and released additional heat in sintering process, favoring the melting of flaky Ni3Al, boosting generation of α-Al2O3 phase, and promoting formation of Ni3(Al, W, Mo) solid solution. With increasing MoO3 content, the tungsten grain size, relative density, and bending strength of sintered alloys increased first and then decreased, while their hardness always increased. Among them, the 1.5WNM alloy exhibited optimal mechanical properties with a bending strength of 1173.11 ± 31.6 MPa and a hardness of 75.5 ± 0.83 HRA (593.5 ± 27.06 HV1). In the salt spray corrosion process, due to uniform distribution of the tungsten grain among binder phases, the formation of loose porous corrosion layer, and the dissolution of MoO3 in local basicity environment in 1.5WNM alloy, its anti-salt spray corrosion property was worse than that of 0WNM alloy.