Tunable magnetocaloric effect in transition metal alloys.
The unpredictability of geopolitical tensions and resulting supply chain and pricing instabilities make it imperative to explore rare earth free magnetic materials. As such, we have investigated fully transition metal based "high entropy alloys" in the context of the magnetocaloric effect. We find the NiFeCoCrPdx family exhibits a second order magnetic phase transition whose critical temperature is tunable from 100 K to well above room temperature. The system notably displays changes in the functionality of the magnetic entropy change depending on x, which leads to nearly 40% enhancement of the refrigerant capacity. A detailed statistical analysis of the universal scaling behavior provides direct evidence that heat treatment and Pd additions reduce the distribution of exchange energies in the system, leading to a more magnetically homogeneous alloy. The general implications of this work are that the parent NiFeCoCr compound can be tuned dramatically with FCC metal additives. Together with their relatively lower cost, their superior mechanical properties that aid manufacturability and their relative chemical inertness that aids product longevity, NiFeCoCr-based materials could ultimately lead to commercially viable magnetic refrigerants.
Department of Physics, University of South Florida, 4202 East Fowler Ave, Tampa, FL 33620.
Dustin D
DD
Belyea
Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, USA.|UTC, Inc., 1270 North Fairfield Road, Dayton, OH 45432, USA.
M S
MS
Lucas
Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, USA.|Wright State University, Dayton, OH 45435, USA.
E
E
Michel
Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, USA.
J
J
Horwath
School of Chemistry and Materials Science, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623.
Casey W
CW
Miller