| The non-exponential and non-linear behavior of relaxing glasses below the glass temperature, Tg, is a well known and poorly understood phenomena that is the subject of much experimental and theoretical effort. The Interstitialcy Theory, which describes glasses as perfect crystals with a few percent of interstitialcy defects, provides an atomic insight into the nature of relaxing glasses. The shear modulus, G, is uniquely sensitive to interstitialcies and provides a convenient way to monitor their changing concentrations.; A non-contact EMAT technique is used to excite and detect a shear wave resonance in bulk amorphous metallic glass Pd40Ni40P 20 during and after a small sudden change in temperature. A shear modulus relaxation is observed with enough precision to determine how its time constant, tau, changes as the relaxation progresses. The results discriminate against models of glassy relaxation commonly found in the literature and are consistent with the Interstitialcy Theory. |
