Microstructure of Nd2Fe17N3 Magnetic Powder Surface With Nano-α-Fe Phases Separated Surface Layer

Abstract

We investigated the application of Nd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> magnetic powder with planar magnetic anisotropy to magnetic field amplification materials at several tens of MHz. Consequently, we succeeded in developing a magnetic property with real permeability ~ 8 and imaginary permeability below 0.8 at 100 MHz using a phosphoric acid coating and a simple heat treatment process in air. In this study, microstructural analysis conducted using transmission electron microscopy and X-ray diffraction revealed that the coating layer became thicker, and the Nd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> surface was phase-separated into nano-sized α-Fe phases and Nd-rich phases, either oxide, oxynitride, or nitride. Additionally, the nano-sized α-Fe phases and the nano-sized Nd-rich phases were oriented over a wide area spanning several hundred nanometers. We concluded that these characteristic structures have led to improved properties.