Plastically deformed Gd-X (X = Y, In, Zr, Ga, B) solid solutions for magnetocaloric regenerator of parallel plate geometry

Abstract

Despite significant progress in the study of materials undergoing first-order magnetic phase transitions accompanied by the so-called giant magnetocaloric effect (MCE), Gd metal still remains the most widely used material in prototypes of magnetic refrigerators due to its significant MCE, good machinability and reasonable mechanical and chemical stabilities. Alloying of Gd enables fine-tuning the Curie temperature of Gd-based solid solutions (all show second-order phase transitions), for graded magnetocaloric materials. Commonly, Gd packed spheres are used as a magnetocaloric working substance in the active magnetic regenerator (AMR) cycle. In this work, we show that the optimized stacking parallel-plate geometry of AMR bed made of Gd is more effective for application at frequencies 1–10 Hz then the packed spheres. We also give a short review on magnetocaloric properties of cold-rolled Gd-X (X = Y, In, Zr, Ga, B) solid solutions. These materials can be produced in the form of thin (∼100 μm) foils/plates to ensure rapid heat exchange between to the heat transfer fluid. Although the magnetocaloric effect decreases in the as-rolled foils, it can be recovered by thermal treatment of the final stacked-plates regenerators. Gd-Y, Gd-In and Gd-Zr solid solutions have magnetocaloric properties, comparable to the MCE of pure Gd in a wide temperature working span up to 37 K, 36 K, and 16 K respectively, which makes them suitable magnetocaloric material systems for testing the fundamental heat exchangers geometries at ambient temperature and in frequencies of 1–10 Hz.