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Sound propagation in thermally-forced copper-nickel alloy
Y. W. Kim and J. H. Raffield

The great majority of metallic alloys are disordered. Disorder is quantified by means of the probability that a constituent atom is part of nanocrystallites within the alloy specimen, and this probability defines the degree of crystallinity. According to the recently developed, statistical physics-based binary alloy model, the disorder can be modified by thermal forcing applied to the alloy specimen. We have examined the effect of thermal forcing of a 55 W%–45 W% copper-nickel wire specimen on the speed of longitudinal sound wave. A wire specimen is heated to temperatures of one-half to 71% of the alloy’s melting point for as long as more than 15 hours, followed by rapid quenching to room temperature. The notion is that the degree of crystallinity has been forced to undergo changes at different thermal forcing intensities. The response has been measured in terms of the changes in sound speed at room temperature. The results of the measurements are analyzed from the standpoint of disorder modification.

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