Low-Temperature Elastic Properties of ZrC and TiC

The elastic constants of zirconium carbide and titanium carbide were determined over the temperature range of 4.2° to 298°K using a pulsed‐ultrasonic phase comparison technique, and are compared to previously determined values for uranium carbide. Since these carbides are of the NaCl structure, only three independent constants are required to describe their elastic behavior. Their values at 298°K are $$\begin{array}{ccc}& {\mathrm{ZrC}}_{\text{0.94}}& {\mathrm{TiC}}_{\text{0.91}}\\ C_{11}& \text{4.720±0.005}& \text{5.145±0.005}\\ C_{12}& \text{0.987±0.005}& \text{1.060±0.002}\\ C_{44}& \text{1.593±0.002}& \text{1.788±0.002}\end{array}$$ all in units of 10¹² dyn/cm². The differences in the elastic behavior of these group IV, transition metal carbides and the monocarbide of uranium are discussed in reference to their different electronic structure.