Advances in Magnetocaloric Properties of Amorphous Alloy Composites
Compared with traditional gas compression refrigeration, magnetic refrigeration has the advantages of high refrigeration efficiency, low noise, small size, green environmental protection and no pollution. As a potential alternative to traditional refrigeration technology, it has attracted the attention of scientific and technological circles around the world. A key issue in the field of magnetic refrigeration is to develop new high-performance magnetic refrigeration materials. Amorphous alloys have disordered atomic structures and metastable properties. Therefore, as magnetic refrigeration materials, they have the advantages of wide refrigeration temperature range, excellent mechanical properties and corrosion resistance compared with crystalline materials, and have broad application prospects in the field of magnetic refrigeration.
The research team of amorphous alloy magnetoelectric functional properties of Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences has long been committed to the development of new amorphous magnetic refrigeration materials and their microscopic mechanism research, and has achieved a series of research results. By introducing structural mixing entropy into amorphous alloys, a series of high-entropy amorphous alloys with excellent magnetocaloric properties were developed. The maximum magnetic entropy change value can reach 15.0 J/kg/K, and the magnetic transition behavior and complex composition structure of the spin glass of the high-entropy amorphous alloy make it have a wider magnetic transition interval (116 K), and then obtain Huge magnetic refrigeration capacity (691 J/kg) [Intermetallics 2015 (58) 31-35; J. Appl. Phys. 2015 (117) 073902; J. Alloys Compd. 2019 (776) 202-206]. The team further used melt drawing equipment to process high-entropy amorphous alloys into micro-wires with high specific surface area and heat transfer efficiency required for practical applications [Intermetallics 2018 (96) 79-83]. In addition, by optimizing the alloy composition and microstructure, a series of amorphous alloys with excellent magnetocaloric properties around room temperature were developed, and the effects of composition, microstructure and magnetic structure on the magnetocaloric properties were studied in detail [Metals 2021 (11) 950; J. Alloys Compd. 2020 (845) 156191; J. Alloys Compd. 2016 (684) 29-33; J Non-Crystl. Solids 2015 (425) 114-117; J. Magn. Magn. Mater. 2018 ( 446) 162-165; J. Magn. Magn. Mater. 2019 (489) 165404; J. Magn. Magn. Mater. 2019 (475) 249-256].
Recently, the team developed a series of Gd-based amorphous nanocrystalline composite magnetic refrigeration materials using melt-pulling technology. This amorphous composite magnetic refrigeration material combines the advantages of Gd-based amorphous alloys and nanocrystals. By optimizing the alloy composition and adjusting the preparation process, the size, quantity and distribution of the nanocrystallized phase can be regulated, and the obtained Excellent magnetocaloric properties. The composite material has a large magnetic entropy change from 70 K to near room temperature, and its magnetic refrigeration capacity can reach 985 J/kg, which is significantly better than other existing crystalline and amorphous magnetic refrigeration materials.
The research work was published in Materials Today Physics 21 (2021) 100528 in a paper entitled “Giant refrigerant capacity in Gd-based amorphous/ nanocrystalline composite fibers”. This research was supported by the National Key R&D Program (2018YFA0703602, 2018YFA0703604), the National Natural Science Foundation of China (51771217, 51827801, 51922102), and the Youth Innovation Promotion Association of the Chinese Academy of Sciences (2019296).
Microstructure and magnetocaloric properties of Gd-based amorphous nanocrystalline composite magnetic refrigeration materials