Structure and Properties of Sm – Co – Fe – Cu – Zr Magnets for High-Temperature Applications

Hard Magnetic Properties and the Features of Nanostructure of High-Temperature Sm-Co-Fe-Cu-Zr Magnet with Abnormal Temperature Dependence of Coercivity

“…The former is mainly controlled by the Curie temperature. The β coefficient is calculated as follows [ 22 , 37 ]: where T 0 and T 1 are the room temperature and operating temperature, respectively. Thus, similar to coercivity, they are dependent on the magnetic hysteresis and composition of magnets, as well as the intrinsic properties of constituting phases.…”

“…The former is mainly controlled by the Curie temperature. The β coefficient is calculated as follows [22,37]:…”

“…Usually, magnets with an operating temperature of 400 °C and above are referred to as the HTPM [ 21 ]. However, such division introduces uncertainty, because Sm-Co-Fe-Cu-Zr PMs with operating temperatures of up to 450 °C may not have an abnormal temperature dependence of the coercivity [ 22 , 23 ].…”

“…It was shown that the contents of Sm, Cu, and Fe significantly affect the coercivity at high temperatures [ 21 ]. The coercivity of magnets with a high Cu concentration is quite high at room temperature, and the absolute value of the negative coefficient β exceeds 0.15%/°C [ 22 ]. Thus, for applications, it is extremely important to identify the physical nature and technological methods [ 25 ], thus allowing for the control of the temperature coefficient of coercivity β in order to achieve the required values of J H c while maintaining the maximum value of remanent induction B r at about 1 kG in the operating temperature range of electric drives.…”