It is low FePt based permanent magnet alloy null expression

摘要

PPROBLEM TO BE SOLVED: To provide a practically useful low-cost nanocomposite permanent magnet alloy having a reduced Pt content and combining satisfactory hard magnetic properties and excellent corrosion resistance in consideration of the fact that a minute permanent magnet having strength and high corrosion resistance with the dimensions in the order of ≤mm is required for the application to a micromachine or the like. PSOLUTION: The Fe-Pt based permanent magnet alloy having a reduced platinum content, having satisfactory hard magnetic properties, and also having excellent corrosion resistance has a composition expressed by formula of FeSB100-a-b/SBPtSBa/SBBSBb/SB[wherein, a and b are atomic%, and satisfy 10 atomic%a≤35 atomic% and 10 atomic%≤b≤35 atomic%], and has a nanocomposite structure comprising an Fe-Pt regular phase with a CuAu(L1SB0/SB) structure and having a mean crystal grain size of ≤300 nm. The Fe-Pt based permanent magnet alloy has less Pt content and satisfactory hard magnetic properties satisfying a residual magnetic flux density (BSBr/SB) of ≥0.6 T, a coercive force (SBi/SBHSBc/SB) of ≥300 kA/m and the maximum energy product (BH)SBmax/SBof ≥60 kJ/mSP3/SPin a state of an alloy thin strip with a wall thickness of 10 to 300 μm obtained by a single roll liquid quenching method, or alloy powder with a diameter of about 10 to 300 μm obtained by an atomizing method as it is or after crystallization heat treatment at 450 to 650°C. PCOPYRIGHT: (C)2006,JPO&NCIPI