Elastic and anelastic properties of metals near their melting points from miscibility gap alloy composites

Abstract

A new method, using Miscibility Gap Alloy composites and Resonant Ultrasound Spectroscopy, has been developed to determine the temperature dependence of elastic and anelastic properties of metals up to and through their melting points. The experimental conditions of high frequency (f~106Hz) and low strain (<10−6) significantly extend the frequency range available for determining, in particular, the high temperature background of acoustic loss seen at temperatures greater than half the melting point. For Sn at T<450K and Bi, the frequency dependence of the loss appears to follow fn with n~0.2, assuming activation energies determined by lattice diffusion or pipe diffusion within dislocations. For Sn there appears to be a temperature interval up to the melting point with n≈1, which could be indicative of premelting. The same approach of using a soft metal matrix to support a second phase has also been demonstrated for measuring acoustic loss in powder samples of LaAlO3. It provides, in principle, a new method for determining elastic and anelastic properties of powder samples with grain sizes down to nanoscale.