Effect of dry thermal oxidation on the microstructure and magnetic properties of SmCo5 permanent magnet

Abstract

Understanding the microstructural changes in SmCo5 because of oxidation and thereby altered magnetic properties will help in designing permanent magnets which could retain their magnetic properties in adverse environments. In this regard, the present study investigates the thermal oxidation of SmCo5 magnets by varying temperature (373−973 K), time (1, 5 h) and pressure (1.013 × 105 and 4.6 × 10−5 Pa). Increased Co segregation towards the surface is found and this impacts the overall oxidation mechanism to a large extent. In the end, the developed oxide-film microstructure and microstructural changes in the bulk are correlated with the induced changes in the magnetic properties.