Hydrogen Decrepitation Behaviors of Novel RE–Fe–B Strip-Casting Alloys Based on Misch Metal

Abstract

To reduce the Nd-Fe-B material cost and balance the utilization of rare earth sources, the misch metal (MM) substitution for Nd in the sintered magnet attracts interest. Under the processing of fabricating Nd-Fe-B magnet, hydrogen decrepitation (HD) is widely used to obtain magnetic powder; however, the HD behaviors of RE-Fe-B strips based on MM may be complex. The HD behaviors of the [(Pr, Nd) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> MM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> ] <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30.8</sub> FebalCo <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.4</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.97</sub> (x = 0-1) strips were studied under 0.2 MPa pressure. We find that it is similar to the Nd-Fe-B, 2:14:1 tetragonal structure of RE-Fe-B strips based on MM which is not broken during hydrogen decrepitating. But the REFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> phase in MM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30.8</sub> FebalCo <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.4</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.97</sub> disappears dramatically as a result of hydrogenation. For the samples with MM, the HD process is quicker and the particle size gets smaller than that for free MM, especially for samples with 35 wt.% MM, which may be attributed to La and Ce elements.