Third-Order Elastic Constants of Magnesium. I. Experimental

The complete set of ten third-order elastic constants of magnesium has been determined from measurements of the hydrostatic-pressure and uniaxial-compression derivatives of natural sound velocities using an ultrasonic pulse-superposition technique. The specimen was neutron irradiated with an integrated exposure of 2 × ${10}^{18}$ (fast) neutrons per ${\mathrm{cm}}^2$ to suppress dislocation effects. The results are $c_{111}=-6.63\mathrm{}$, $c_{112}=-1.78\mathrm{}$, $c_{113}=+0.30\mathrm{}$, $c_{222}=-8.64\mathrm{}$, $c_{123}=-0.76\mathrm{}$, $c_{133}=-0.86\mathrm{}$, $c_{333}=-7.26\mathrm{}$, $c_{144}=-0.30\mathrm{}$, $c_{155}=-0.58\mathrm{}$, and $c_{344}=-1.93\mathrm{}$ in units of ${10}^{12}$ dyn ${\mathrm{cm}}^{-2\mathrm{}}$.