NdFeB Magnets with Improved Temperature Characteristics

Abstract

ABSTRACTThe temperature dependence of magnetic properties for NdFeCoB alloys were investigated. It is well known that dysprosium substitution for neodymium increases the intrinsic coercivity. Aluminum also improves the intrinsic coercivity, Hci, at room temperature but impairs the Curie temperature and the intrinsic coercivity at elevated temperatures. The rate of increase of the Hci with increasing dysprosium in the NdFeCoB system is less than when dysprosium is added to the NdFeB system. A combination of aluminum and dysprosium is more effective than aluminum alone in raising Hci. Molybdenum addition into the NdDyFeCoB alloy was found to reduce the temperature coefficients of Br and Hci. Temperature coefficients of Br and Hci obtained on a Nd10Dy5Fe67Co10Mo1Al1B6 alloy are -0.07 %/°C and -0.4 %/°C respectively.