Abstract
The equili-brium of the system Cobalt-Silicon is thoroughly investigated by means of thermal, microscopic, X-ray, dilatometric and magnetic analyses, and a new equilibrium diagram is proposed. In this system there exist four compounds, i.e., Co2Si(ε), CoSi(η), CoSi2 and Co3Si(γ); the first three melt without decomposition at 1332°, 1460° and 1336° respectively, while the last one is formed by the following peritectic reaction ;
melt+δ_??_Co3Si (γ).
The compound Co2Si changes to δ phase at 1320°: the change is probably an allotropic one. The compound CoSi2 has a slight thermal change at 1258°, but it is not an'allotropic change. The compounds Co3Si2 and CoSi3, Proposed by K. Lewkonya, do not exist. The α_??_β allotropic transformation point of Cobalt rises with the increasing content of Silicon, and decomposes to P and S by the peritectoid reaction at 755° and 6.5per cent silicon.
