Coercivity and nanostructure of melt-spun Ti-Fe-Co-B-based alloys

Authors

Wenliang Zhang, University of Nebraska, LincolnFollow
Ralph A. Skomski, University of Nebraska-LincolnFollow
Arti Kashyap, University of Nebraska - LincolnFollow
Shah R. Valloppilly, University of Nebraska-LincolnFollow
Xingzhong Li, University of Nebraska-LincolnFollow
Jeffrey E. Shield, University of Nebraska-LincolnFollow
David J. Sellmyer, University of Nebraska-LincolnFollow

Date of this Version

2016

Citation

AIP ADVANCES 6, 056001 (2016)

http://dx.doi.org/10.1063/1.4942552

Comments

C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

Abstract

Nanocrystalline Ti-Fe-Co-B-based alloys, prepared by melt spinning and subsequent annealing, have been characterized structurally and magnetically. X-ray diffraction and thermomagnetic measurements show that the ribbons consist of tetragonal Ti₃(Fe,Co)₅B₂, FeCo-rich bcc, and NiAl-rich L2₁ phases; Ti₃(Fe,Co)₅B₂, is a new substitutional alloy series whose end members Ti₃Co₅B₂ and Ti₃Fe₅B₂ have never been investigated magnetically and may not even exist, respectively. Two compositions are considered, namely Ti_11+xFe_37.5-0.5xCo_37.5−0.5xB14 (x = 0, 4) and alnico-like Ti₁₁Fe₂₆Co₂₆Ni₁₀Al₁₁Cu₂B₁₄, the latter also containing an L2₁-type alloy. The volume fraction of the Ti₃(Fe,Co)₅B₂ phase increases with x, which leads to a coercivity increase from 221 Oe for x = 0 to 452 Oe for x = 4. Since the grains are nearly equiaxed, there is little or no shape anisotropy, and the coercivity is largely due to the magnetocrystalline anisotropy of the tetragonal Ti₃(Fe,Co)₅B₂ phase. The alloy containing Ni, Al, and Cu exhibits a magnetization of 10.6 kG and a remanence ratio of 0.59. Our results indicate that magnetocrystalline anisotropy can be introduced in alnico-like magnets, adding to shape anisotropy that may be induced by field annealing.