The effects of AB2 (A=Zr,Hf,Ti) additions on the free-iron content in ingotswith the initial composition of Nd2.2Fe14B1.1

Research output: Contribution to journalArticle

Authors

  • Ken Kirby
  • Azizah Shaaban
  • David Kennedy
  • Andy J. Williams

Colleges, School and Institutes

External organisations

  • Brookes Bell

Abstract

Additions of zirconium diboride (ZrB2), to small scale (~1 g) arc-melted (AM) and larger scale (5 kg) book mould (BM) cast alloy with the composition Nd2.2Fe14B1.1 (near to stoichiometric Nd2Fe14B) have been shown to be a very effective means of eliminating the free-iron content, which is present as a result of the peritectic nature of the Nd2Fe14B phase. The effect of zirconium diboride in reducing free-iron content has been determined (1) magnetically by means of the Honda-Owen plots on the BM alloys and (2) by image analysis using scanning electron microscopy for both AM and BM alloys. Generally, for the BM alloys, both sets of measurements exhibited good agreement with a progressive reduction in the free-iron content with increasing additions of ZrB2. Without any subsequent homogenisation treatment, zero free-iron was achieved in the AM and BM cast condition, after an addition of just 1 mol% of ZrB2. Closely similar behaviour was observed with up to 1 mol% additions of the other Group 4 diborides, TiB2 and HfB2. High resolution scanning electron microscopy indicated that the diborides were embedded largely within the areas of Nd-rich material.

Details

Original languageEnglish
Article number167098
JournalJournal of Magnetism and Magnetic Materials
Volume513
Early online date2 Jun 2020
Publication statusE-pub ahead of print - 2 Jun 2020

Keywords

  • Metals and alloys, Permanent magnets, Rare earth alloys and compounds, Mechanical alloying, Microstructure, Phase diagrams