Novel magnetocaloric composites with outstanding thermal conductivity and mechanical properties boosted by continuous Cu network

Magnetic refrigeration based on the magnetocaloric effect is expected to trigger technological revolu-tion in the refrigeration industry due to the merits of high energy efficiency and complete elimination of greenhouse gas emissions. However, the implementation of this emerging technology is hindered by some challenges in the magnetocaloric materials, e.g., low thermal conductivity (lambda) and poor mechanical properties. This paper reports a novel magnetocaloric composite that is characterized by continuous Cu networks within the (Mn,Fe)2(P,Si) magnetocaloric matrix. This unique microstructure is designed with the aid of finite-element simulations and experimentally realized by hot pressing the (Mn,Fe)2(P,Si)/Cu core/shell powders. High-resolution transmission electron microscope revealed good interfacial coherence between the matrix and the binder, which is highly desirable to reduce the interfacial thermal resistance. The magnetocaloric composites with such a novel microstructure exhibit a high lambda of 20.4 Wm -1K -1 and a large maximum compressive strength of 570 MPa, which are the best comprehensive properties for room -temperature magnetocaloric materials ever reported. Consequently, this work offers a promising way to tackle the bottleneck problems of low thermal conductivity and the brittleness of the magnetocaloric materials, which may accelerate the practical application of magnetic refrigeration.(c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.