Annealing effect on structural, microstructural and magnetic properties of nanocrystalline Er-Co-B alloys for permanent magnet applications.

In this paper, we have examined the structural, microstructural, and magnetic properties of Er - Co - B compounds. High-energy ball milling has been used to homogeneous the stoichiometric mixture of Er, Co and B as starting materials to synthesis the Er 17 Co 75 B 8 powders. The samples are crystallized in the hexagonal CaCu 5 - structure type with P6/mmm space group. Their structural and magnetic properties were assumed systematically as a function of annealing temperature. The structural properties were studied by means of X-ray diffraction and the microstructural properties via Scanning Electron Microscopy. The magnetic phase with abbreviated formula ErCo 4.5 B 0.5 and global formula Er 16.67 Co 75 B 8.33 was a dominate phase. These compounds exhibit a high coercivity of 8 kOe at room temperature for ErCo 4.5 B 0.5 annealed at 1073 K for 1/2 h. These magnets with high H C are appropriate to permanent magnet applications. We have also applied to the Approach of Saturation in to Magnetization (ASM). The results were understood in according to the model of random magnetic anisotropy. Image 1 • Structural and magnetic properties of ErCo 4.5 B 0.5 alloys have been investigated. • The structural and magnetic properties vs annealing temperature (T a) were studied. • At 293 K, H C reaches its maximal value about 0.8T for T a = 1073 K. • The results were interpreted in the framework of random magnetic anisotropy model. • Some parameters were extracted such as the local magnetic anisotropy constant. [ABSTRACT FROM AUTHOR]