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National Institute for Material Science

Dr. Hossein Sepehri-Amin, a researcher of Nanostructure Analysis Group, et al. won the Gottfried Wagener Prize 2015.

2015.07.01
  The winners of the Gottfried Wagener Prize 2015 were announced at the award ceremony at the Grand Hyatt Tokyo on June 30, 2015, and Dr. Hossein Sepehri-Amin, a researcher of Nanostructure Analysis Group, and Dr. Takahiro Akiya (team member), a post doc researcher, won the Gottfried Wagener Prize.

  The Gottfried Wagener Prize honors young scientists in Japan for path-breaking and application-oriented research work in the areas of Mobility, Materials, Life Sciences and Energy & Industry. In each of these four research areas a prize of 2,500,000 Yen is awarded.

  They won the award in the area of "Materials" for the work entitled: "Development of Dy-free high performance Nd-Fe-B permanent magnets by engineering of grain boundary phase".
  • "Development of Dy-Free High Performance Nd-Fe-B Permanent Magnets by Engineering of Grain Boundary Phase"

      "Nd-Fe-B (Neodymium) based magnets are essential components in the energy saving technology in traction motors of hybrid/electric vehicles and wind turbine generators. However, the coercivity (resistance against magnetization reversal) of Nd-Fe-B sintered magnets is low and decreases under rising temperatures, preventing such magnets from storing magnetization. Hence, it is necessary to increase coercivity under such conditions. The current approach to improve coercivity of Nd-Fe-B magnets is to partially substitute Nd (Neodymium) with heavy rare earth elements such as Dy (Dysprosium). However, as Dy is a scarce natural resource and it also reduces magnetization, it is worthwhile to find alternative processes to increase the coercivity of Nd-Fe-B magnets.
      Dr. Hossein Sepehri-Amin and his colleagues at the National Institute for Materials Science have studied the microstructure–coercivity relationships of Nd-Fe-B magnets using detailed analyses and micromagnetic simulations. They found that the existence of large amounts of iron at grain boundaries is responsible for the low coercivity of Nd-Fe-B magnets. Dr. Sepehri-Amin and his team have developed a technique to diffuse low-melting point (non-magnetic) Nd-Cu eutectic alloys through grain boundaries in Nd-Fe-B magnets leading to a decrease of iron concentration from grain boundaries. This process led to a substantial enhancement of coercivity. They have also applied this technique to hot-deformed Nd-Fe-B magnets composed of smaller grains than those of sintered magnets, succeeding in producing Dy-free samples with a higher energy density whose coercivity was equivalent to Nd-Fe-B sintered magnets containing 4wt.% Dy. This grain boundary engineering technique has the potential to produce Dy-free Nd-Fe-B magnets on an industrial level."
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