The elastocaloric effect in the vicinity of the martensitic transition of a Cu-Zn-Al single crystal has been studied by inducing the transition by strain or stress measurements. While transition trajectories show significant differences, the entropy change associated with the whole transformation (S t ) is coincident in both kinds of experiments since entropy production is small compared to S t . The values agree with estimations based on the Clausius-Clapeyron equation. The possibility of using these materials for mechanical refrigeration is also discussed. DOI: 10.1103/PhysRevLett.100.125901 PACS numbers: 65.40.Gÿ, 75.30.Sg, 81.30.Kf Caloric effects are expected to occur under the application of an external field to a given material. The elastocaloric effect [1] is the mechanical analogue of the magnetocaloric effect that has received considerable attention in the recent years owing to its potential use for environmentally friendly refrigeration [2]. The magnetocaloric effect is related to the isothermal change of entropy or the adiabatic change of temperature that takes place within a material when a magnetic field is applied or removed. This effect originates from the coupling between the magnetic sublattice and an externally applied magnetic field and thus occurs in any magnetic material. A large effect is expected in the vicinity of field-induced, firstorder phase transitions where large entropy changes should occur [3]. By analogy, the elastocaloric effect is defined as the isothermal change of entropy or the adiabatic change of temperature that takes place when a mechanical field (stress) is applied or released in a given material. Indeed, this effect is expected to be a consequence of the coupling between an external applied stress and the lattice. Continuing with the analogy, a large elastocaloric effect is also foreseen in systems undergoing stress-induced, first-order phase transitions. Good candidates to show this effect are shape-memory alloys. These materials undergo a diffusionless purely structural transition from a cubic to a lower symmetry phase that can be stress induced [4]. Actually, shape-memory properties are related to this transition and refer to the ability of these systems to remember their original shape after severe deformation [5].In contrast to magnetism, instead of controlling the applied stress (or force) which is the variable thermodynamically equivalent to the magnetic field, in mechanical experiments, the system is usually driven by controlling the strain (generalized displacement) which is the conjugated variable to the stress in the way that magnetization is the conjugated variable of the magnetic field. In magnetic systems, due to the difficulty in controlling magnetization, magnetization-driven experiments aimed at studying the magnetocaloric effect have not, to our knowledge, been reported. Thus, comparing results from both field-or stress-driven and magnetization or strain-driven experiments is of general interest since constraining the (generalized) displacement pr...

by jerky propagation of phase fronts related to the appearance of avalanches. In this paper we describe a full analysis of this avalanche behavior using calorimetric heat flux measurements and acoustic emission measurements. Two different propagation modes, namely smooth front propagation and jerky avalanches, were observed in extremely slow measurements with heating and cooling rates as low as a few 10 Avalanches appear to be more common for heating rates faster than 5 10 -3 K/h whereas smooth front propagation occurs in all calorimetric measurements and (almost) exclusively for slower heating rates. Repeated cooling runs were taken after a waiting time of 1 month (and an intermediate heating run). Correlations between the avalanche sequences of the two cooling runs were found for the strongest avalanche peaks but not for the full sequence of avalanches. The memory effect is hence limited to strong avalanches.3

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We study temperature changes at the reverse strain-induced martensitic transformation in a Cu–Zn–Al single crystal. Infrared thermal imaging reveals a markedly inhomogeneous temperature distribution. The evolution of the contour temperature maps enables information to be extracted on the kinetics of the interface motion.