The Bordoni peak in copper single crystals at megahertz frequencies

The Bordoni peak in high-purity copper single crystals has been investigated by measuring the attenuation of longitudinal waves at 10.2 and 30.6 MHz using a conventional ultrasonic pulse technique with a single quartz transducer. The crystals, of (100), (110) and (111) orientations, were deformed by compression, and the temperature dependence of the ultrasonic attenuation was measured after applying resolved shear stresses ranging up to 60 N mm -2 . The results lead to the following conclusions: (i) the temperature of the Bordoni peak in copper single crystals is essentially independent of the orientation; (ii) the temperature of the Bordoni peak in copper single crystals decreases as the prior deformation is increased up to a resolved shear stress near 28 N mm -2 , and then increase slightly for higher prior stresses; and (iii) conditions that favour deformation by easy glide give rise to a relatively large Bordoni peak.