Abstract
Metal injection moulding in conjunction with hot isostatic pressing was applied to prepare MIM418 superalloy. Densification behaviour, precipitated phases and tensile properties of the alloy were characterised. Relative density of 97.6% is obtained after vacuum sintering at 1240°C, and near full dense alloy is achieved after HIPing. High volume fraction (57%) of near cuboidal γ’ phase with average particle size of 0.52 μm precipitates homogeneously in γ matrix. Small amount of fine carbides with average particle size of 0.22 μm distribute mainly along grain boundaries and in grain interior. Average grain size of the superalloy is estimated to be ∼26 μm. Uniformly distributed precipitates and fine grain size lead to significant improvement of mechanical properties. The tensile strength, yield strength and ductility of MIM418 superalloy achieve 1425 MPa, 1004 MPa and 19.4% respectively, which are much higher than that of the cast K418 superalloy.
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