In situ observation of the reaction of scandium and carbon by neutron diffraction

The formation of scandium carbides by reaction of the elements has been investigated by in situ neutron diffraction up to 1823 K. On heating, the recrystallization of α-Sc occurs between 1000 and 1223 K. The formation of Sc2C and ScC (NaCl-B1 type structure) phases has been detected at 1323 and 1373 K, respectively. The formation of a new orthorhombic scandium carbide phase was observed at 1473(50) K. Once the scandium carbides are formed they are stable upon heating or cooling. No other phases were detected in the present study, in which the system was always carbon saturated. The thermal expansion coefficients of all phases have been determined, they are constant throughout the temperature interval studied.

Research highlights▶ Exist two ScC cubic phases with B1-structure type differing in site occupancy of C. ▶ A new orthorhombic scandium carbide phase is formed at 1473(50) K. ▶ The recrystallization of alpha-Sc occurs between 1000 and 1223 K.