Production of reactive sintered nickel aluminide material

Reactive sintering process for producing a shaped body of the nickel aluminide compound Ni.sub.3 Al, which comprises sintering a compacted shaped mass of an initmate mixture of unmilled elemental nickel powder in a particle size of less than about 3 .mu.m and unmilled elemental aluminum powder in a particle size of about 15 .mu.m, in a stoichiometric atomic ratio generally corresponding to the compound Ni.sub.3 Al and in which the nickel powder is present in an amount of about 85.5-87.5 wt.% of the mixture, by heating the mass in a substantially dry inert atmosphere to an elevated sintering temperature of about 550.degree.-750.degree. C. sufficiently to initiate an exothermic reaction, and at a heating rate of at least 3 K./min. for consequent progressive generation of a transient liquid below the melting point of the aluminum powder and at the corresponding eutectic temperature, and upon initiation of the exothermic reaction continuing the sintering for a total sintering time of at least about 2 seconds and at most about 10-15 minutes, to form a densified shaped body containing the nickel aluminide compound Ni.sub.3 Al having a porosity of less than about 8%.

Hot isostatic reactive sintering process for producing a fully dense shaped body of the nickel aluminide compound Ni.sub.3 Al, which comprises cold isostatically compacting an intimate mixture of elemental nickel powder and elemental aluminum powder in a stoichiometric atomic ratio generally corresponding to the compound Ni.sub.3 Al to form a compacted shaped mass, sealing the compacted shaped mass in a container which has been evacuated to form a sealed container containing the compacted shaped mass under vacuum, and hot isostatically compacting the mass by simultaneously heating and pressing the sealed container sufficiently to initiate an exothermic reaction and generate a transient liquid below the melting point of the aluminum powder and at the corresponding eutectic temperature, and upon initiation of the exothermic reaction continuing the heating and pressing sufficiently to form a fully densified shaped body containing the nickel aluminide compound Ni.sub.3 Al.

Process which comprises sintering a compacted shaped mass of an intimate mixture including powder particles containing nickel and powder particles of elemental aluminum in a stoichiometric atomic ratio of the nickel and aluminum in the mixture generally corresponding to the compound Ni.sub.3 Al, by heating the mass in a substantially dry inert negative pressure environment to an elevated sintering temperature sufficiently to initiate an exothermic reaction and generate a transient liquid below the melting point of the aluminum and at the corresponding eutectic temperature, and upon initiation of the exothermic reaction continuing the heating sufficiently to form a densified shaped body containing the nickel aluminide compound Ni.sub.3 Al.