THIS PROPOSAL FOR RESEARCH ADDRESSES THE NEED FOR NEW, HIGH-TEMPERATURE MATERIALS OF UNUSUAL STRUCTURAL AND PHYSICAL PROPERTIES.

THIS PROPOSAL FOR RESEARCH ADDRESSES THE NEED FOR NEW, HIGH-TEMPERATURE MATERIALS OF UNUSUAL STRUCTURAL AND PHYSICAL PROPERTIES. THE CHEMICAL STABILITY AND THE TENDENCY FOR EUTECTIC SOLIDIFICATION WOULD BE EXPLORED FOR SPECIFIC PERIODIC GROUP III AND IV METAL OXIDE-METAL NITRIDESYSTEMS. TO DO THIS, BLENDED OXIDE-NITRIDE POWDERS WOULD BEPRESSED INTO PELLETS, HEATED ON W, MO, OR TA STRIP HEATERS TO FORM MELTS, AND THEN SOLIDIFIED. FREE ENERGY OF FORMATION DATA WOULD BE USED TO ESTIMATE THE REGIONS OF EXISTENCE AND THE CHEMICAL STABILITY OF THESE SYSTEMS. THE NECESSARY OXYGEN AND NITROGEN PARTIAL PRESSURES WOULD BE MAINTAINED OVER MELTS AND DURING THE SOLIDIFICATION PROCESS SO AS TO ENHANCE THE COEXISTENCE OF THE OXIDES AND NITRIDES.THE HIGH-TEMPERATURE STABILITY AND SOLIDIFICATION MORPHOLOGYFOR THE SYSTEMS A1203-TIN, Y203-TIN, ZR02-TIN, A1203-ZRN, Y203-ZRN, AND ZR02-ZRN WOULD BE NOTED. THOSE SYSTEMS SHOWING A TENDENCY TO FORM, UPON SOLIDIFICATION, EUTECTIC-LIKE STRUCTURES WOULD THEN BE CANDIDATES FOR BULK DIRECTIONAL SOLIDIFCATION VIA OUR COLD-CRUCIBLE AND INTERNALZONE GROWTH TECHNIQUES DURING PHASE II. PHOTOMICROGRAPHS OFTHESE SOLIDIFIED STRUCTURES ALONG WITH MICROHARDNESS, FRACTURE TOUGHNESS, AND X-RAY PHASE DATA WOULD BE GATHERED. ANY TENDENCIES TO FORM OXYNITRIDES AS A EUTECTIC COMPONENT WOULD BE FOLLOWED UP.