FABRICATION OF NI-SHEATHED NICKEL ALUMINIDE WIRES FROM MECHANICALLY ALLOYED PRECURSORS

Cold working by swaging and shape-rolling of mechanically alloyed comp act is proposed to fabricate the composite wires. The bulk mechanical alloying is useful here to produce a sufficient amount of homogeneousl y refined mixture of nickel and aluminum in bulk. Through heat treatme nt at 873 K for 10 h, Ni-sheathed green wires can be converted to a co mposite wire of nickel aluminides. Since mechanical alloyed powder com pact is used as a starting material for fabrication of composite wires , regularization reaction into nickel aluminides can be ignited at rel atively low temperatures. The bulk mechanical alloying is used to yiel d the refined elemental mixture without any formation of intermetallic compounds, so that sufficient workability should be preserved for the subsequent wiring process. The present method is supposed to be promi sing to make near-net shaping of nickel aluminides. Warm extrusion met hod is also utilized in this method instead of heat treatment. (C) 199 7 Elsevier Science S.A.