| 摘要 |
A process for casting and preparing an ingot of a beta-phase NiAl-based material, particularly for use in PVD coating processes. The method entails melting a nickel-aluminum composition having an aluminum content below that required for stoichiometric beta-phase NiAl intermetallic so as to form a melt that includes nickel and Ni3Al. Aluminum is then added to the melt, causing an exothermic reaction between nickel and aluminum as the melt equilibrium shifts from Ni3Al to NiAl. However, the aluminum is added at a rate sufficiently low to avoid a violent exothermic reaction. The addition of aluminum continues until sufficient aluminum has been added to the melt to yield a beta-phase NiAl-based material. The beta-phase NiAl-based material is then solidified to form an ingot, which is then heated and pressed to close porosity and homogenize the microstructure of the ingot.
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