Molten aluminum and nickel cast onto a steel block exothermically react and produce molten nickel monoaluminide, NiAl, which is simultaneously joined to the steel. The heat of the exothermic reaction is transferred to the steel block, and steel near the surface of the block is melted. The depth of the melted steel increases with both the initial temperature of the steel block and the thickness of the produced NiAl. Iron from the melted steel dissolves in the molten NiAl, and an intermetallic compound of NiAl-Fe pseudo-binary system is produced. During solidification of the intermetallic compound, it is strongly joined to the steel. The NiAl-Fe intermetallic compound has an excellent resistance to oxidation and corrosion.
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