EAGER: Novel Nitride-Based Exchange-Spring Nanocomposites

University Of Memphis, Memphis TN

Investigators

Abstract

Novel Nitride-Based Exchange-Spring Magnetic Nanocomposites TECHNICAL: With escalating power demands, there is an increased emphasis on producing high power density electrical machines for use as motors, generators, actuators, etc. A promising new technology to produce these power-dense machines employs exchange spring permanent magnets (ESPM). ESPMs are magnetically ?hard? and ?soft? phases that are exchange-coupled to give high energy products, (BH)max. High (BH)max values have been reported for rapidly-solidified, melt-spun, and ball-milled rare-earth-transition metal (RE-TM) intermetallic ESPMs. In addition nitride-based ESPMs are promising candidates for permanent magnets whose performance could exceed that of the NdFeB-Fe RE-TM ESPMs. In this research a novel low-temperature synthesis technique is examined for fabricating nitride-based nanocomposites with high (BH)max values and operating temperatures. This synthesis technique is based on laminating hard magnetic phase nanopowders with soft phases, catalytic nitrogenation of the hard and soft phases, and low temperature densification using pulse plasma compaction. This approach should provide greater grain size control and exchange-coupling between the hard and soft phases, lower temperature synthesis of the nitride phases, lower temperature compaction, and greater corrosion resistance. The PI intends to explore the synthesis of these novel nitride-based nanocomposites, to understand their properties and to optimize their compositions to obtain high energy product permanent magnets. The high payoff of this work derives from the low temperature catalytic nitrogenation of the soft iron phase in the nanocomposites. If successful, this study will yield two important breakthroughs, a new avenue for the synthesis of nitride-based composite materials and specific guidance for developing more energy efficient, compact devices using high energy product permanent magnets. NONTECHNICAL: This project is a promising new technology for the production of nitride-based exchange-coupled permanent magnets for power-dense machines. This approach moves away from current, poorly-defined, nanoscale morphologies to spatially and compositionally engineered nanostructures. This novel design approach offers previously unattainable magnetic properties by exploiting magnetocrystalline and shape anisotropy of materials. The research provides processing breakthroughs and fundamental understanding that should facilitate future commercial development of a new class of high performance permanent magnets. The research effort is coupled to an educational initiative aimed at teaching research methodology to graduate and undergraduate students.