High resolution lattice measurements on CuZnAl austenite-martensite transition

The need for efficient, environmentally-friendly heating and cooling systems is becoming a particular priority worldwide. The use of heat pumps based on solid-state phase transformation (elasto-caloric effect) is promising for this purpose. Among all materials, copper-based alloys are the best candidates in terms of material resources and CO2/kg emissions. However, functional fatigue endurance needs to be increased (10⁷ cycles required) before realistic devices can be developed. We propose to search in the CuZnAl beta phase (a model Shape Memory type of alloy exhibitnig giant elastocaloric properties), optimal compositions that would fullfill the crystallographic supercompatibility criteria. These criteria are based on the measurements of the eigenstrains of the stretch matrix describing the crystallographic transformation from bcc austenite to monoclinic martensite. In this experiment we plan to measure lattice spacing of different CuZnAl alloys during their thermal transformation.