Fabrication of Ni-sheathed nickel aluminide wires from mechanically alloyed precursors

Abstract

Cold working by swaging and shape-rolling of mechanically alloyed compact is proposed to fabricate the composite wires. The bulk mechanical alloying is useful here to produce a sufficient amount of homogeneously refined mixture of nickel and aluminum in bulk. Through heat treatment at 873 K for 10 h, Ni-sheathed green wires can be converted to a composite wire of nickel aluminides. Since mechanical alloyed powder compact is used as a starting material for fabrication of composite wires, regularization reaction into nickel aluminides can be ignited at relatively low temperatures. The bulk mechanical alloying is used to yield 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 promising to make near-net shaping of nickel aluminides. Warm extrusion method is also utilized in this method instead of heat treatment.