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arXiv · 2405.11636

Ultraslow calorimetric studies of the martensitic transformation of NiFeGa alloys: detection and analysis of avalanche phenomena

José-María Martín-Olalla·Antonio Vidal-Crespo·Alejandro F. Manchón-Gordón·Francisco Javier Romero·Javier S. Blázquez·María Carmen Gallardo·Clara F. Conde
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Abstract

We study the thermal properties of a bulk Ni55Fe19Ga26 Heusler alloy in a conduction calorimeter. At slow heating and cooling rates (1K/h), we compare as-cast and annealed samples. We report a smaller thermal hysteresis after the thermal treatment due to the stabilization of the 14M modulated structure in the martensite phase. In ultraslow experiments (40mK/h), we detect and analyze the calorimetric avalanches associated with the direct and reverse martensitic transformation from cubic to 14M phase. This reveals a distribution of events characterized by a power law with exponential cutoff $p(u) \propto u^{-\varepsilon}\exp(-u/\xi)$ where $\varepsilon\sim 2$ and damping energies $\xi=370$uJ (direct) and $\xi=27$uJ (reverse) that characterize the asymmetry of the transformation.

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José-María Martín-Olalla, Antonio Vidal-Crespo, Alejandro F. Manchón-Gordón, Francisco Javier Romero, Javier S. Blázquez, María Carmen Gallardo, Clara F. Conde. 2024-05-19. Ultraslow calorimetric studies of the martensitic transformation of NiFeGa alloys: detection and analysis of avalanche phenomena. https://doi.org/10.1007/s10973-024-13206-4

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