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Pr-Fe-B die-upset magnets exhibited a lower remanence and a higher coercivity than analogous Nd-Fe-B magnets, with the microstructure of both magnets exhibiting similarities. Enhanced magnetic domain wall pinning and increased coercivity in Pr-Fe-B magnets was due to the thick intergranular phase. Hot-worked Pr2Fe14B magnets were obtained from melt-spun ribbons.

Die upsetting melt-spun ribbons of hot-pressed Pr-Co and Sm-Co pressure alloys produce the magnetically anisotropic PrCo5 type of magnets. Magnetic coercivity improves on low-level carbon addition to the alloys. Whereas increased carbon addition maximizes coercivity and drastically reduces magnetic remanence, PrCo5 type magnets have a higher saturation magnetization phase and substituting Sm for Pr and Fe for Co which would greatly improve the magnet's coercivity and remanence.

Melt spun Pr-Co alloys are investigated to optimize and enhance their permanent magnet characteristics. Of the different elemental additives investigated, carbon is the only element capable of improving the properties, especially coercivity, considerably from the Pr16Co84 composition, the optimum values of remanance, intrinsic coercivity and energy product for the binary Pr-Co systems. The values are increased for Pr18Co76C6. PrCo5 constituted melt-spun ribbons in both the compounds. PrCo7 and PrCo2Cx, two new rare earth-cobalt phases, were discovered during the process.

The use of high-remanence rapidly solidified Nd-Fe-B alloys as a starting material for die-upset magnets was investigated. The results showed that remanence increased along with the die-upset (DU) level and reached a maximum of 13.5 kG at 70% DU for ternary Nd-Fe-B magnets. Nonuniform deformation also had a detrimental effect on remanence. The decreased coercivity can be offset by heat treatments, dysprosium substitutions and low-level additives.

Microstructures of GdxAg100-x alloy ribbons prepared by melt spinning are examined by x-ray diffraction and transmission electron microscopy to evaluate their magnetic and magneto-caloric characteristics. The Gd-only ribbons exhibit a single field-induced entropy change (Delta-S) peak near 280 K. Delta-S shows another peak in the 100-120 K range for GdxAg100-x alloys, indicating an amorphous, ferromagnetic Gd-Ag component. The Gd50Ag50 ribbons comprise antiferromagnetic crystalline GdAg.

Differential scanning calorimetric estimations of the Curie temperatures of cobalt and iron diffusion in die-upset Nd-Fe-Co-B-magnets from metal-spun ribbons reveal a marked diffusion between ribbons that cause microstructure alteration and the deformation of the rigid 2-14-1 magnet. Cobalt diffuses across ribbons during hot working to rearrange the transition metal accumulation over the magnet. Homogenization of the metal composition is, however, not thorough.

Characterization of the magnetic and structural properties of rare earth-iron (R-Fe) compounds reveals that the compounds have a monoclinic crystal structure and that the Ce member of the groups with Cr and Ti has the minimum magnetization value, unit cell and Curie temperature. The properties of the Ce ion indicates that it is tetravalent. Magnetization data reveal that Nd3(Fe,Cr)29 and Nd3(Fe,Ti)29 display spin orientations at temperatures of 145 and 235 K, respectively.

Studies of phase formation in melt-spun Nd-Fe-Mo-Ti alloys at different quench rates and quench wheel surface velocities show that slow quench velocity facilitates ThMn(12)-type crystal structure development while high wheel velocities result in the TbCu(7)-type structure. The stability of the ThMn(12) structure is higher at the Mo-rich end than at the Ti-rich end, indicating that compositions at the Ti-rich end are more susceptible to quenching. Heat treatments of alloys show that annealing temperatures higher than 1,000 degrees centigrade are essential for ThMn(12) crystal structure formation.

Melt spinning of rare-earth cobalt alloys yields ribbons which have the hexagonal PrCo5 phase as the major phase. Consolidation of these ribbons at very high pressures and temperatures yields fully-dense hot-pressed magnets with isotropic magnetic properties. Nearly 75% saturation magnetization is exhibited by these magnets.

R2Fe14B compounds with rare-earth components such as Ce, Pr, Nd and Er are experimentally investigated to determine the transverse and longitudinal moduli. The elastic constants are determined using a resonant ultrasound method. The compounds have spin reorientations and ultrasonic features are exhibited near the spin orientation at Curie temperature.

Nitrided melt-spun Nd-Fe-Mo ribbons exhibit hard magnetic properties which are studied as functions of quench rate, nitriding time, wheel velocity (Vs) and composition. The magnetic properties which are studied as a function of Vs exhibited is analogous to that found on direct-quenched Nd-Fe-B ribbons.

The magnetic properties of Tb2Fe14B were investigated using neutron powder diffraction analysis. The results showed that all magnetic moments were collinear with the x-axis. The Tb and Fe moments were antiparallel. In addition, the Tb moments approached their free ion value at low temperatures. Minor variations were observed in the nuclear coordinates through the whole R2Fe14B family.

Determines the Sm[sub 2]Fe[sub 17]N[sub x] permanent magnets prepared by nitriding melt-spun samarium-iron (Sm-Fe) precursor ribbons. Application of the x-ray diffraction technique; Factors attributed to higher coercivities; Effect of nitrogen on the composition and crystal structure of Sm-Fe ribbons.