The Effect of Electromagnetic Stirring on the Microstructure Evolution of Cu-15%Co Alloy

Abstract

Cu-15%Co alloys have been synthesized by an induction furnace adopting electromagnetic stirring (EMS). The liquid-liquid separation behavior and the peritectic reaction under a forced melt flow were analyzed. The specimens were subjected to a conventional induction melting as well as enhanced melt stirring by a two-side electromagnetic stirrer. The stirred ingots showed a significant improvement in dispersivity and homogeneity of the Co-rich phase. Comparing the specimens subjected to different current intensities, we observed strong changes in the phase fraction, the degree of segregation, and the grain size. EMS had an effect of reducing the amount and size of Co-rich droplets and enhancing the amounts of small equiaxed dendrites and dendrite fragments, which led to a more dispersive distribution of α-Co phase and refined the grains of Cu-rich phase. We observed a considerable increase in the fraction of peritectic Cu-rich phase with increasing current intensity of EMS, indicating that the peritectic reaction was promoted by EMS. EMS also reduced the macrosegregation of Co-rich phase in both the vertical and radial direction of the ingot when the current intensity was appropriate.