Permanent Magnets with Improved Mechanical Properties for Propulsion

Rare earth permanent magnets of the Nd2Fe14B family are brittle with poor mechanical properties. The poor material toughness poses serious problems in the manufacture of magnets, assembly in devices and integrity of motor components during spinning. Thetraditional powder metallurgy method of improving mechanical properties by refining microstructures via substitutions of rare earth Dy, Pr for Nd and alternate transition metals for iron yield only incremental improvement that is not sufficient. Wepropose to obtain quantum leap in magnetic and mechanical property improvement in this project by combining four innovative approaches which are (1) exchange spring magnet powders via spark erosion for advantageous particle morphology and magneticperformance, (2) powder particle coatings for corrosion proof and mechanical strength, (3) DMC compaction for full density, and (4) higher strength and net shape rotor fabrication via DMC to enhance magnetic performance with good mechanical robustness.This integrated approach will produce material with the best mechanical strength and toughness while yielding best magnetic performance. The proposed approach of making rotors with high performance powders will revolutionize motor designs by cutting thesize, weight and cost. The applications are related to brush and brushless DC electric motors for the Navy, DOD, and commercial industry. DC electric motors have wide application throughout the Navy, from motors and actuators to instrumentation, pumps,and propulsion. Permanent magnet materials are required for many other Navy and DOD applications including motors and generators for ships, torpedo applications, aircraft and spacecraft systems; actuators, inductors, inverters and regulators for flightcontrol surfaces, sensors and other Navy and aircraft components.