Permanent Magnets with Improved Mechanical Properties for Propulsion

Perrmanent magnets are very brittle and are prone to cracking during transportation and assembly in devices such as motors and generators. Conventional routes of alloying and microstructure modifications have produced only limited success in improving theabove mentioned properties of intermetallic compounds. In addition, the permanent magnetscorrode when exposed to oxygen. In industrial usage, the finished magnets are covered by additional coatings to protect from corrosion. All these additional processes add to mass, size and cost of the end product and complicate the assembly process. Wepropose to use combination of novel powder and magnet processing approach via DynamicMagnetic Compaction (DMC) to obtain high performance magnets with improved toughness, ductility and corrosionresistance. This will involve using high performance powder coating on micron size and nano size Exchange Spring Permanent Magnet (ESPM) powdersto achieve high magnetic performance, high ductility, toughness and corrosion resistance. We anticipate the presence of soft magnetic iron phase in ESPM composites will contribute to increased toughness and ductility. In addition, exchange coupled magnetpowders will be coated with nano-meter thick (5 - 100 nm) dielectric/metallic layers to form nano composites. Such composites have potential to yield superior magnetic, mechanical, thermal and electrical performance that is not available in currentsystems. Magnets with improved properties such as toughness, ductility and corrosion resistance along with high magnetic perormance will be beneficial in Permanent Magnet (PM) motors for ship, underwater vehicle propulsion and magnetic levitationapplications. Inaddition, these permanent magnets will also benefit commercial motor and generator applications.