Rapidly Solidified Neodymium-Iron-Boron Permanent Magnets details the basic properties of melt spun NdFeB materials and the entire manufacturing process for rapidly solidified NdFeB permanent magnets. It covers the manufacturing process from the commercial production of the melt spun or rapidly solidified powder, to the production and properties of both isotropic bonded Nd and hot deformed anisotropic NdFeB magnets. In addition, the book discusses the development and history of bonded rare earth transition metal magnets and the discovery of the NdFeB compound, also covering melt spun NdFeB alloys and detailing the magnetization process and spring exchange theory. The book goes over the production of melt spinning development, the operation of a melt spinner, the processing of melt spun powder, commercial grades of NdFeB magnetic powder and gas atomized NdFeB magnetic powders. Lastly, the book touches on the major application and design advantages of bonded Nd Magnets. - Features a unique perspective as the author is not only the inventor of NdFeB magnetic powder, but also played a key role in developing many of the technologies covered - Provides a comprehensive look at the history, fundamental properties, production processes, design and applications of bonded NdFeB magnets - Includes discussion of the rare earth supply challenge, politics, and systems as it impacts bonded NdFeB magnets

In early in 1985 the potential of FeNd (Pr) B (SI) alloys for permanent magnet development was demonstrated. The progress under consideration was initiated in April 1983, to study the properties of these materials in more details and in particular to understand the origin of magnetic hardening by correlating the magnetic properties with the microstructure determined by transmission electron microscopy. The magnetic properties of melt-spun Fe-R-B alloys have been examined in the whole rare-earth series. The tetragonal Fe14R2B phase occurs in all alloys studied except in Eu and Yb containing alloys. The Curie temperature of this phase increases from about 170C in Fe14CeB to 375 for Fe14Gd2B and then decreases for the heavier rare-earths and is only 320 C in Fe14Ho2B. In heavy rare-earths, a second phase with a higher Curie temperature approx.(470 C) has also been observed. The nature of this phase is not yet known. The magnetic hysteresis properties of melt-spun Fe-light rare-earth-boron alloys were examined and maximum coercivities were found to scale with the anisotropy fields.

Rapid solidification of novel mixed rare earth-iron-boron, MRE2Fe14B (MRE = Nd, Y, Dy; currently), magnet alloys via high pressure gas atomization (HPGA) have produced similar properties and structures as closely related alloys produced by melt spinning (MS) at low wheel speeds. Recent additions of titanium carbide and zirconium to the permanent magnet (PM) alloy design in HPGA powder (using He atomization gas) have made it possible to achieve highly refined microstructures with magnetic properties approaching melt spun particulate at cooling rates of 105-106K/s. By producing HPGA powders with the desirable qualities of melt spun ribbon, the need for crushing ribbon was eliminated in bonded magnet fabrication. The spherical geometry of HPGA powders is more ideal for processing of bonded permanent magnets since higher loading fractions can be obtained during compression and injection molding. This increased volume loading of spherical PM powder can be predicted to yield a higher maximum energy product (BH)max for bonded magnets in high performance applications. Passivation of RE-containing powder is warranted for the large-scale manufacturing of bonded magnets in applications with increased temperature and exposure to humidity. Irreversible magnetic losses due to oxidation and corrosion of particulates is a known drawback of RE-Fe-B based alloys during further processing, e.g. injection molding, as well as during use as a bonded magnet. To counteract these effects, a modified gas atomization chamber allowed for a novel approach to in situ passivation of solidified particle surfaces through injection of a reactive gas, nitrogen trifluoride (NF3). The ability to control surface chemistry during atomization processing of fine spherical RE-Fe-B powders produced advantages over current processing methodologies. In particular, the capability to coat particles while 'in flight' may eliminate the need for post atomization treatment, otherwise a necessary step for oxidation and corrosion resistance. Stability of these thin films was attributed to the reduction of each RE's respective oxide during processing; recognizing that fluoride compounds exhibit a slightly higher (negative) free energy driving force for formation. Formation of RE-type fluorides on the surface was evidenced through x-ray photoelectron spectroscopy (XPS). Concurrent research with auger electron spectroscopy has been attempted to accurately quantify the depth of fluoride formation in order to grasp the extent of fluorination reactions with spherical and flake particulate. Gas fusion analysis on coated powders (dia.

The process of high temperature phase transition of rare earth permanent-magnet alloys is revealed by photographs taken by high voltage TEM. The relationship between the formation of nanocrystal and magnetic properties is discussed in detail, which effects alloys composition and preparation process. The experiment results verified some presumptions, and were valuable for subsequent scientific research and creating new permanent-magnet alloys. The publication is intended for researchers, engineers and managers in the field of material science, metallurgy, and physics. Prof. Shuming Pan is senior engineer of Beijing General Research Institute of Non-ferrous Metal.

These papers provide an interesting collection of contributions on fundamental magnetic behaviour, microstructural studies, processing methods and applications of rare earth, iron-rich, high performance permanent magnets. The remarkably versatile nature of the Nd-Fe-B-type alloys with respect to magnet processing is very evident in these proceedings. Thus there are papers which describe the production of magnets by the die-upset-forging of melt-spun ribbon, by cold-compaction of melt-spun-ribbon with soft metals, by mechanical alloying and by hot working of cast material. Work is also reported on the production of new permanent magnets from melt-spun material based on the alloys Nd4Fe78B18 and SmFe11.5Ti1.04. Both these alloys look promising and the former appears to be close to commercial exploitation.