The effect of microstructure on magnetic properties of TLP bonded Sm 2 Co 17 hard magnets
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The effect of microstructure on magnetic properties of TLP bonded Sm2Co17 hard magnets Hossein Mostaan1 · Mahdi Rafiei2 · Mohammad Mahdi Oraei1 · Ehsan Baharzadeh2 Received: 26 February 2020 / Accepted: 28 April 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract A Sm2Co17 permanent magnet was successfully transient liquid phase bonded using AWS BNi-2 interlayer at 1100 °C for 60 min. Microstructural evolutions and chemical composition changes after TLP bonding of the samples were analyzed using optical microscopy, scanning electron microscopy and energy-dispersive spectroscopy. The changes of magnetic properties of the base material due to the TLP process were evaluated using vibrating sample magnetometry. It was found that the bonded sample by 50-μm-thick interlayer foil majorly contained athermally solidified zone and brittle second phase, indicating that the bonding time is not sufficient for joining, while the bonded sample by 25-μm-thick foil was almost solidified isothermally. Also, the results showed that a considerable increase in coercivity, remanence and also maximum energy product was occurred after TLP bonding of S m2Co17 permanent magnet. This increase was mainly attributed to the strong magnetic exchange coupling between FeCo- and Fe-rich borides (as soft magnets) and Sm–Co matrix (as hard magnet). Keywords Transient liquid phase · Hard magnets · Vibrating sample magnetometry · SmCo alloys · Microstructure
1 Introduction Recent developments in various industrious such as military fields have encouraged electrochemical designer to design systems that perform at higher temperatures with higher speeds. For increase in performance of many power generations, distribution and utilization systems, advanced magnetic materials are required [1]. High-performance permanent magnets are usually intermetallic compounds of rare earth and transition metals. The first of new rare-earth magnets was samarium–cobalt, which become available in 1970s followed by neodymium–iron–boron magnets (NdFeB) in the mid-1980s. SmCo magnets exist in two alloy varieties. In Sm–Co alloy system, Sm1Co5 (SmCo 1:5) is the original alloy and Sm2Co17 (SmCo 2:17) is the more common used.
* Hossein Mostaan H‑[email protected] 1
Department of Materials and Metallurgical Engineering, Faculty of Engineering, Arak University, 38156‑8‑8349 Arak, Iran
Advanced Materials Research Center, Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
2
Magnets based on Sm–Co system have attracted considerable attention of researchers due to these advantageous [2–7]: • • • • •
High coercive force of about > 2 T High curie temperature (greater than 800 °C) High magnetocrytalline anisotropy Low temperature coefficient of remanence and coercivity High maximum energy product
These distinctive properties make S m2Co17-type hard magnets usually irreplaceable for high-temperature applications in the temperature range of above 450 °C and over a variety of environmental condit
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