Peculiarities of viscosity and solidification of the Cr–C melts in the vicinity of the eutectic composition

•We study viscosity of the Cr–C (10–17 at.% С) melts and their solidification.•The viscosity minimum is found in isotherms near 14.5 at.% C.•The Cr–C melts have nonequilibrium crystallization from 1680 °C at 20–100 °C/min.•Cr23C6 is formed from melts only on cooling of 13.5–14.5 at.% C melts lower than 1612 °C.

The relationship between short-range ordering of the Cr–C melts (10–17 at.% C) and their structures in the solid state has been investigated by the analysis of viscosity of these liquid alloys and their solidification at various cooling rates (20–100 °C/min). The minimum has been found in the concentration dependences of viscosity of the Cr–C melts in the vicinity of 14.5 at.% C. It has been shown that on cooling at various rates (from 20 to 100 °C/min) the Cr–C melts are crystallized by non-equilibrium mechanism with the formation of α-Cr solid solution and the α-Cr/Cr7C3 non-equilibrium eutectic, the latter being decomposed into equilibrium phases, α-Cr and Cr23C6. A τ-phase (Cr23C6) has been observed to form directly from liquid phase only in the Cr–C liquid alloys in the narrow concentration interval in the vicinity of the eutectic composition (13.5 to 14.5 at.% С) when the melt is cooled from the temperatures below the peritectic transformation temperatures (1612 °C).