THE PROPERTIES OF COBALT–IRON ALLOYS PREPARED BY POWDER ROLLING *

Abstract

A series of cobalt–iron alloys containing 0–15% iron was prepared in the laboratory by using powder-metallurgical techniques. The alloys were made by mixing commercially pure cobalt and iron powders, roll compacting the blended powders into strip, and directly hot rolling the roll-compacted strip into fully dense alloy strip. The procedures and equipment used to prepare the alloys are described and the structural and mechanical properties of the resulting strip are discussed as a function of alloy composition. The study indicated that a 7% iron addition suppressed the α (f.c.c.) ⇌ ϵ (h.c.p.) transformation in cobalt. The ductility of the alloy series increased with increasing iron content and X-ray and dilatometric analysis related this improvement to the elimination of the ϵ (h.c.p.) phase. One striking feature of the experimental results was that changes in the structural and mechanical properties were achieved without alloy homogenization.

The forming characteristics of the alloys were optimized and the 7% iron alloy was chosen for development studies. This alloy was subsequently prepared using production equipment in the Sherritt Gordon Powder Rolling Mill and the forming properties of the resulting strip were shown to be equivalent to those of the laboratory material.