Effect of Zr Addition on Magnetic Properties of TbCu7-Type Sm–Fe–N Powder Synthesized by Low-Temperature Ca Reduction Diffusion Process

Abstract

The effect of the addition of Zr on magnetic properties of anisotropic TbCu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> -type Sm-Fe-N powders prepared by the low-temperature reduction diffusion process was investigated. At the reduction diffusion temperature of 873 K, the TbCu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> -type Sm-Fe phase ratio decreased with an increase in the Zr content. At a higher reduction diffusion temperature of 973 K, a TbCu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> -type Sm-Fe phase was obtained regardless of the amount of Zr added. Furthermore, the Th <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Zn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sub> -type Sm-Fe phase was obtained without the addition of Zr. Therefore, it was indicated that the addition of Zr can stabilizes the TbCu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> -type Sm-Fe phase at high temperatures. By nitriding the obtained powder, a TbCu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> -type Sm-Fe-N powder was obtained; however its magnetic properties deteriorated as the amount of Zr increased. Microstructural analysis revealed that the element ratio Zr/Sm in the TbCu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> -type Sm-Fe-N particles saturated at approximately 0.05, and the excess Zr was consumed to form the ZrFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> phase on the outside of the particles. It was concluded that the ZrFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> phase results in the deterioration in the magnetic properties of the powder.