Fe-Nb-Ta-Co-Mo系半硬質磁性合金「Recalloy」の特性について

Abstract

Measurements of the magnetic properties, the thermal expansion, the electrical resistivity and the hardness were carried out for Fe-0-3 mass%Nb-4-0 mass%Ta-20 mass%Co-3 mass%Mo alloys. All the alloys used in this study were water-quenched from 1323 K, cold-drawn to 97.2% reduction in area and subsequently reheated at 673-1273 K for the period less than 18 ks. The magnetic properties of alloys depend remarkably on the contents of niobium and tantalum, and the reheating temperature and time.When water-quenched, cold-drawn and subsequently reheated at 973 K for 1.8 ks, an Fe-1.5%Nb-1.5%Ta-20%Co-3%Mo alloy exhibits the following values: B8 at 8 kA·m−1=1.96 T, Br=1.86 T, Br⁄B8=0.95, Hc=1.89 kA·m−1, \sqrt(BH)max⁄BrHc=0.95, the mean thermal expansion coefficient αT at 273-313 K=9.0×10−6 K−1, the electrical resistivity ρ=0.262μΩ·m and Vickers hardness Hv=391. Also, using ferro-niobium for metallic niobium as raw material, an Fe-1.5%Nb-0.5%Ta-20%Co-3%Mo alloy reheated at 1023 K for 0.6 ks exhibits the following values: B8=2.00 T, Br=1.86 T, Br⁄B8=0.95, Hc=1.75 kA·m−1, \sqrt(BH)max⁄BrHc=0.95, αT=8.8×10−6 K−1, ρ=0.265 μΩ·m and Hv=444.Thus the Fe-Nb-Ta-Co-Mo alloys “Recalloy” is practically suitable to the reed blade in remanent reed switch. Further, there is such a big merit that the expensive cobalt content in Recalloy is 1/2-1/4 as compared with that of semihard magnetic materials having most practical use.