| abstract |
The R-TM-B permanent magnet member having an improved corrosion resistance comprising an R-TM-B permanent magnet body having a composition by weight of 5-40% of TM and 0.2-8% of B, wherein R represents one or more rare earth metals including Y, TM represents a transition metal based on Fe, and B represents boron is provided with a nickel plating layer and then with a chromate coating layer, which may be then subjected to an immersion treatment in an alkali solution. The magnet body may be subjected to etching before nickel plating. In a further aspect such an R-TM-B permanent magnet member is provided with a lower metal plating layer selected from Ni, Ni-S, Ni-P, Cu, Cr and Sn and an upper metal plating layer selected from Ni, Ni-P, Gu, Cr, Sn, said lower and upper metal plating layers being different from each other, and said upper metal plating layer being less noble by, 100mV or more, than said lower metal plating layer with respect to a natural potential in a 5%-NaCl aqueous solution. |