Influence mechanism of Fe content on the magnetic properties of Sm2Co17-type sintered magnets: Microstructure and Microchemistry

The effects of the Fe content on the magnetic properties and the microstructures of the Sm(Co0.925-xFexCu0.05Zr0.025)(7.74) (x = 0.21-0.31) sintered magnets were investigated. The influence mechanism of the Fe content on the remanence (B-r) and intrinsic coercivity (H-cj) of the magnets were studied depending on the comprehensive analysis of the cellular/lamellar structures and the element distribution of the cell and cell wall phases. The incomplete cellular structure, lower Cu content and higher Fe content of the cell wall phases were considered as the main reasons for the low H-cj of the magnet with x = 0.31. The slope of linear increase of the B-r of the magnet with x range from 0.27 to 0.31 is lower than that of the magnet with x range from 0.21 to 0.27 indicating a lower B-r enhancement efficiency which is mainly caused by the high Fe content of the cell wall phase of the magnet with x > 0.27. A high maximum energy product ((BH)(max)) of 32.36 MGOe with a H-cj of 34.62 kOe was obtained for the Sm(Co0.655Fe0.27Cu0.05Zr0.025) 7.74 magnet. (C) 2019 Elsevier B.V. All rights reserved.