Nickel Subsilicide, Ni₂Si

Di-nickel Silicide or Nickel Subsilicide, Ni₂Si, is obtained by heating nickel and 10 per cent, of silicon in a carbon crucible in an electric furnace. It is a stable, steel-grey substance, density 7.2 at 17° C. Fluorine attacks it with incandescence at ordinary temperatures, and chlorine at red heat. It dissolves readily in hydrogen fluoride, less so in hydrogen chloride; aqua regia decomposes it completely.

The freezing-point curve of nickel and silicon indicates the existence of several other silicides, namely, Ni₃Si, Ni₃Si₂, NiSi, and Ni₂Si₃. A tetranickel silicide, Ni₄Si, has been isolated. Density curves, however, apparently indicate the existence of three silicides only, namely, Ni₂Si, NiSi, and Ni₃Si₂.