1997 TMS Annual Meeting: Tuesday Abstracts

RARE EARTHS, SCIENCE, TECHNOLOGY AND APPLICATIONS: Session IV: Melts and Metals Reduction Processing

Session Chairpersons: Timothy W. Ellis, Kulicke and Soffa Industries, Inc., 2101 Blair Mill Road, Willow Grove, PA 19090; Ramana G. Reddy, Dept. of Metallurgical Eng., University of Alabama, Tuscalossa, AL 35487

2:00 pm

ANODE EFFECT IN NEODYMIUM OXIDE ELECTROLYSIS: Rudolf Keller, Kirk T. Larimer, EMEC Consultants 4221 Roundtop Road, Export, PA 15632

In the electrolysis of neodymium oxide from a molten fluoride electrolyte, anode effects may occur at the carbon anodes, interfering with smooth cell operation. In laboratory experiments, we attempted to circumvent this problem selecting electrolytes with a high oxide concentration, possibly at relatively low rare earth content, but cathodic deposition was not satisfactory. A regime at higher cell voltage was discovered to yield good cell performance, but evolution of considerable amounts of fluorocarbon compounds suggested that a reactive treatment of the off-gases would be necessary for environmental acceptability. Subsequent experimentation at low cell voltage revealed conditions for satisfactory operation without occurrence of anode effects and without any formation of CF4 and C2F6.

2:30 pm

THERMODYNAMIC MODELING OF CALCIOTHERMIC REDUCTION OF NdF3: P.T. Velu, R.G. Reddy, Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487

Production of neodymium metal by reduction of NdF3 with calcium in the presence of calcium chloride is studied. The thermodynamic calculations of the reduction process was carried out using method of minimization of Gibbs energy. Yield of neodymium metal was calculated as a function of temperature and salt composition. Nd increased with increase in temperature and also increase in CaCl2. Impurity content of the alloy decreased with increase in CaCl2. The calculated data is an excellent agreement with the large scale experimental data.

3:00 pm BREAK

3:30 pm

IMPROVEMENT OF MAGNETIC PROPERTIES OF NANOCOMPOSITE NdFeB MELT SPUN RIBBONS BY ELEMENT SUBSTITUTION: W. C. Chang, S. H. Wu, Department of Physics, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Taiwan, China; B.M. Ma, C. O. Bounds, Rhone-Poulenc, Rhone-Poulenc Rare Earths and Gallium, CN 7500, Cranbury, NJ 08512

The magnetic properties of the nanocomposite NdFeB melt spun ribbons are strongly determined by the remanence, coercivity and the squareness of its demagnetization curve. In this paper, three approaches in improving the magnetic properties of -FE/Nd2Fe14B type nanocomposite melt spun ribbons will be addressed: (1) the effect of Co substitution for Fe on the remanence enhancement (2) the effect of La substitution for Nd on the improvement of remanence and the squareness of the demagnetization curve and (3) the effect of Cr substitution for Fe on the enhancement of the coercivity and the squareness of the demagnetization curve.

4:00 pm

THE MAGNETIC PROPERTIES AND CRYSTALLIZATION PHENOMENA OF MELT EXTRACTED Nd9.8Fe90.2-XBX (X=6 through 11) FILAMENTS: Q. Chen, B. M. Ma, C.O. Bounds, Rhône-Poulenc, Rare Earths and Gallium, CN 7500, New Jersey

Recently, Nd-lean and/or boron-rich melt spun materials have attracted attention as potential materials for bonded magnet applications. Since the alloys can deviate significantly from the stoichiometric Nd2Fe14B composition, additional phases are usually present in the products. The size and volume fraction of these phases play important roles in determining the strength of exchange coupling interaction between phases and, consequently, the magnetic properties obtained. It is of interest to know how the Nd and/or boron contents impact the crystallization behavior and the magnetic properties of these materials. An alloy series of Nd9.8Fe90.2-xBx, where x=6 through 11 was prepared by a newly developed melt extraction technique at various wheel speeds.