Ultrasonic nonlinearity parameters and third-order elastic constants of copper between 300 and 3 °K

The ultrasonic harmonic generation technique has been used to extend measurement of the nonlinearity parameters of copper to 3 °K. Comparison of these data and combinations of truly adiabatic third-order elastic (TOE) constants with predictions of simplified models show that a central force, nearest neighbor model accounts reasonably well for the behavior of copper in the regions of 45 and 200 °K and less well at other regions. The central force, nearest neighbor model also gives a good qualitative explanation for the temperature dependence of the combinations of TOE constants that are measured in this investigation.