Publication Date

6-19-2021

Department

Ames Laboratory; Materials Science and Engineering; Physics and Astronomy

Campus Units

Materials Science and Engineering, Physics and Astronomy, Ames Laboratory

Report Number

IS-J 10527

DOI

10.1016/j.jallcom.2021.160866

Journal Title

Journal of Alloys and Compounds

Volume Number

883

First Page

160866

Abstract

The Ce(Co1-xFex)4.4Cu0.6 (0 ≤ x ≤ 0.19) is a composite, hard magnetic system that is based on the CaCu5-type structure (1:5). It shows both, unique magnetic and microstructural features that are essential for permanent magnets, e.g., exceptional squareness of the 2nd. quadrant of the magnetization loops and microstructural features typically needed for pinning. Samples solidified in alumina crucibles are coarse-grained and often clearly faceted and readily align in a magnetic field. X-ray, SEM, and TEM analyses show a 1:5-type single-phase material when quenched from high temperature, which, after heat treatment, transforms into a laminar coherent nanostructure through the formation of a dense array of extended intercalated regions. These extended intercalated regions are comprised of segments of the Ce2Ni7–type structure (2:7) which segregate into various closely related precipitates forming a nanostructure similar to the SmCo5 - Sm2Co17 composites seen in Sm-Co permanent magnets. Based on TEM and Lorentz microscopy of well-aligned single grain particles, the magnetic domains’ reversal mechanism is regulated by anisotropy fluctuations occurring along the easy direction of magnetization and strong exchange interactions between the matrix and defects (e.g.: stacking faults). Lorentz microscopy suggests the domain wall is not physically pinned by the defect, but rather is offset/deflected when it interacts with the defect. The Lorentz and magnetization data suggest that defects cause a bending of the moment away from the c axis inside the grains.

DOE Contract Number(s)

AC02-07CH11358

Language

en

Publisher

Iowa State University Digital Repository, Ames IA (United States)

Available for download on Sunday, June 19, 2022

Included in

Metallurgy Commons

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