The obje ctives of the research are to develop new iron-based magnetic materials in bulk and in thin film form. Emphasis is placed on rapid solidification, and an exploratory evaluation of novel laser methods of film preparation. The intrinsic magnetic properties of these materials are to be determined and studies carried out of their metallurgical microstructure and its relation to hysteresis. Theoretical modelling of both intrinsic and extrinsic magnetic properties is to be run in parallel with the experimental studies, as a guide to optimizing the magnetic properties.
New iron based magnetic materials were developed in bulk and in thin film form. Emphasis is placed on rapid solidification, and an exploratory evaluation of novel laser methods of film preparation. The intrinsic magnetic properties of these materials were determined and studies carried out of their metallurgical microstructure and its relation to hysteresis. Theoretical modelling of both intrinsic and extrinsic magnetic properties were run in parallel with the experimental studies, as a guide to optimising the magnetic properties.
Extensive work on the thorium manganese(12) structure family of alloys R(iron(12-x-)M(x)), where R is a rare earth x lies between 1 and 2 and M equals titanium, vanadium, molybdenum, etc has established the crystal field and exchange interactions for this family. For permanent magnet applications, the composition samarium(iron(11)titanium) has the best intrinsic properties, and useful coercivity is obtained in nanocrystalline, melt spun ribbons. Each grain is a single domain, and a new model of coercivity is based on an analogy with the random magnetic anisotropy model of amorphous magnetism. Other new materials include a series of derivatives based on the thorium(2)nickel(17) and thorium(2)zinc(17) structures, including interstitial nitrides and carbides, and the R(6)iron(11)gallium(3) compounds. A new gas phase interstitial modification process has been developed to produce powders of 2:17 and 1:12 compounds with greatly enhanced Curie temperature and anisotropy field. Iron based thin films have also been made by thermal evaporation laser sputtering and laser chemical vapour deposition.
THE RESEARCH IS IN TWO MAIN PARTS:
THE FIRST INVOLVES RESEARCH AND DEVELOPMENT OF RAPIDLY SOLIDIFIED RARE-EARTH-IRON-RICH ALLOYS PREPARED BY MELT SPINNING.
THE SECOND PART IS RELATED TO THE CHARACTERIZATION OF METALLIC MAGNETIC MATERIALS IN THE FORM OF THIN FILMS USING ADVANCED LASER AND OTHER TECHNIQUES.
FILMS OBTAINED FROM SUCH MATERIALS WILL BE CHARACTERIZED AND COMPARED WITH THOSE OBTAINED BY CONVENTIONAL EVAPORATION AND SPUTTERING. THE POTENTIAL OF THE VARIOUS METHODS FOR PREPARING FILMS SUITABLE FOR MAGNETO-OPTIC RECORDING WILL BE ASSESSED.
THE ORIGINALITY OF THE PROPOSED RESEARCH IS THAT, IN AN ATTEMPT TO IMPROVE THE MAGNETIC PROPERTIES OF THE EXISTING PHASE OF THE ND-FE-B, THE PRECIPITATION HARDENING PROCESS WILL BE EMPLOYED. ALSO MODELLING OF THE MICROSTRUCTURE WILL BE STUDIED BY THE PREPARATION OF NOVEL MAGNETIC MULTILAYERED STRUCTURES AND THROUGH INNOVATIVE DEVELOPMENT OF LASER METHODS FOR MAGNETIC ALLOY FABRICATION.
POTENTIAL ECONOMIC IMPACT IS FORESEEN AS A RESULT OF IMPROVEMENT OF THE ND-FE-B MAGNETS, DISCOVERY OF NOVEL FE-RICH TERNARY MAGNET PHASES, AND THROUGH THE THIN FILM MULTILAYERS IN DEVICE MINIATURIZATION AND MAGNETIC RECORDING DEVICES. ULTIMATELY, THE EMERGENCE OF MICROMAGNETIC TECHNOLOGY WILL CREATE SUBSTANTIAL NEW MARKETS FOR PERMANENT MAGNET DEVICES.
Funding SchemeCSC - Cost-sharing contracts
OX1 3RH Oxford