Abstract
This work reports the elastic shear moduli, internal friction, and specific heat of the B2 cubic ordered alloy AuZn as functions of temperature. Measurements were made on single-crystal and polycrystalline samples using resonant ultrasound spectroscopy, semiadiabatic calorimetry and quasistatic stress-strain measurements. Our results confirm that this alloy exhibits the shape-memory effect and a phase transition at 64.8 K that appears to be second-order (continuous) from the specific heat data. The acoustic dissipation does not peak at the transition temperature as expected but instead rises well into the low-temperature phase. The low-temperature limiting Debye temperature value Θd = 219 K, obtained from a linear fit of C/T versus T 2 from T = 0.59 K to T = 5.3 K is in favourable agreement with the value calculated from the acoustic data Θ = 207 K, using a T = 0 linear extrapolation of the shear moduli. It is argued that the combination of equiatomic composition and a low transformation temperature constrain the chemical potential and its derivatives to exhibit behaviour that lies at the borderline between that of a first-order (discontinuous) and a continuous phase transition.