Pentachromium Dicarbide, Cr₅C₂

Pentachromium Dicarbide, Cr₅C₂, can be prepared in quantity2 by melting a mixture of chromium and a finely powdered chromium-carbon alloy containing 11.16 per cent, of carbon in a magnesia crucible at 1800° to 1850° C. After repeatedly washing the product with 2N hydrochloric acid until no more chromium dissolves, the carbide, Cr₅C₂, is obtained practically pure. It forms silvery crystals, of density 6.915 at 24.8° C. It is not attacked by aqua regia, and melts without appreciable decomposition at 1665° C.