Investigation of martensitic structure in elastocaloric CuZnAl alloys

The need for efficient and environmentally friendly heating/cooling systems is increasing. The use of heat-pump based on solid state phase transformation are promising, in particularly elasto-caloric materials. CuZnAl alloys (b-brass) are on a material resource and CO2 emission perspectives among the best candidates. Elasto-caloric effect is based on a non displacive crystallographic transition between a high symmetry crystal structure, austenite (cubic) and lower symmetry one, martensite (monoclinic), activated around room temperature thermally or by shear stress. The main bottleneck toward applications is the short fatigue life, due to the lattice mismatch between both phases. Optimizing the composition for high lattice compatibility would allow to reach 10 cycles. We aim at fine crystallographic charactrizations of the transformation on unexplored compositions using μLaue diffraction coupled with a novel in situ technique allowing high resolution Bragg energy determination.