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Effective Grain Pinning Revealed by Nanoscale Electron Tomography
Journal of Applied Physics (2011)
  • Y. Q. Wu, Iowa State University
  • W. Tang, Iowa State University
  • K. W. Dennis, Iowa State University
  • N. Oster, Iowa State University
  • R. W. McCallum, Iowa State University
  • I. E. Anderson, Iowa State University
  • M. J. Kramer, Iowa State University
The grain pinning behavior of TiC particles in a rapidly solidified MRE-Fe-B (MRE = Nd + Y + Dy) nanocrystalline hard magnet was studied using electron tomography (ET). The 3D reconstruction overcomes the inherent 2D nature of conventional transmission electronmicroscopy (TEM) to reveal how this grain boundary phase controls the nanoscale structure in the rapidly solidified alloy. The 3D reconstruction was performed on the optimally annealed alloy (750 °C/15 min) with hard magnetic properties of Mr = 8.1 kGs, Hc = 6.2 kOe, (BH)max = 11.2 MGOe measured at 300 k. The sampled volume, 425 × 425 × 92.5 nm3, contains more than 20 grains of the RE2-14-1 phase and more than 70 TiC nanoparticles. The TiC grains’ shapes depend on their sizes and locations along the grain boundary. Most of the TiC particles are oval or short rod like shapes and range from 5 nm to 10 nm. TiC particles less than 10 nm formed between adjacent 2-14-1 grains, while the largest ones formed at triple junctions. There are ∼1.7 × 108 TiC particles within a 1 mm volume in the alloy. This accounts for the strong grain boundary pinning effect, which limits grain growth during annealing.
Publication Date
April 1, 2011
Citation Information
Y. Q. Wu, W. Tang, K. W. Dennis, N. Oster, et al.. "Effective Grain Pinning Revealed by Nanoscale Electron Tomography" Journal of Applied Physics Vol. 109 Iss. 7 (2011)
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