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Recrystallization of GdCo(5)

IP.com Disclosure Number: IPCOM000074161D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Gambino, RJ: AUTHOR [+2]

Abstract

Rare earth cobalt intermetallics with the CaZn(5) structure, e.g., CdCo(5) can be recrystallized from a molten aluminum solution contained in a commercial Al(2)O(3) crucible. A mixture of the elements with the atomic ratio Gd-5Co-2A1 was heated in an RF furnace in an argon atmosphere to about 1000 degrees C and cooled by slowly (20mm/hr) lowering the crucible out of the RF coil. The resulting ingot contained lath shaped dendritic crystals several mm long from a melt with a total volume of about (10)/3/mm. The crystals grew predominately on the bottom and sides of the crucible indicating that GdCo(5)is the primary phase, i.e., the first phase to crystallize on cooling the melt. X-ray diffraction patterns of the crushed ingot show GdCo(5)as the major phase with lattice constants a = 4.92 Angstroms and c = 4.

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Recrystallization of GdCo(5)

Rare earth cobalt intermetallics with the CaZn(5) structure, e.g., CdCo(5) can be recrystallized from a molten aluminum solution contained in a commercial Al(2)O(3) crucible. A mixture of the elements with the atomic ratio Gd-5Co-2A1 was heated in an RF furnace in an argon atmosphere to about 1000 degrees C and cooled by slowly (20mm/hr) lowering the crucible out of the RF coil. The resulting ingot contained lath shaped dendritic crystals several mm long from a melt with a total volume of about (10)/3/mm. The crystals grew predominately on the bottom and sides of the crucible indicating that GdCo(5)is the primary phase,
i.e., the first phase to crystallize on cooling the melt. X-ray diffraction patterns of the crushed ingot show GdCo(5)as the major phase with lattice constants a =
4.92 Angstroms and c = 4.11 Angstroms as compared to 4.977 Angstroms and
3.967 Angstroms for stoichiometric GdCo(5)/4/. An increase in 'a' and a decrease in c is associated with excess Co in the RECo(5) structure/4/. The shift in lattice constants observed may have been due to excess Co or possibly to aluminum contamination.

Snake domains, characteristic of bubble domain materials in zero magnetic field, were observed in thin (50 to 100 mu m) polished sections of crystals grown by this method. The domain walls were relatively mobile compared to those observed in crystals prepared by arc melting, indicating the superior quality of the solution grown crystals. It was found, however, that fields as high as approx. 1000 oe were not sufficient to collapse the snake domains into bubble domains.

On the basis of the binary phase diagrams of cobalt,/5/ selected initially were five metals, which form cobalt rich low melting eutectics, as potential solvents for GdCo(5). The elements selected were Au, Al, Pb, Sb and Sn. Mixtures with the 1:5:2 Gd:Co:Metal ratio were heated...