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Type: Artigo de evento
Title: Study Of Heat Treatment On The Magnetocaloric Properties Of Gd 5(si 2ge 2) Alloy [estudo Do Tratamento Térmico Sobre As Propriedades Magnetocalóricas Da Liga Gd 5ge 2si 2]
Author: Alves C.S.
Gama S.
Coelho A.A.
Plaza E.J.R.
Carvalho A.M.G.
Persiano A.I.C.
Abstract: The Gd 5(Ge 1-xSi x), x ≤ 0.5 based alloys are pontential candidates for magnetic refrigeration in the range ∼20 - ∼290 K. The use of these alloys in near room temperature applications offer considerable environmental benefits by eliminating ozone depleting, greenhouse, or hazardous gas/liquids refrigerants. Another advantage of magnetocaloric refrigerators is that the cooling power can be varied by scaling form milliwats to a few hundred watts as the cooling efficiency of magnetic refrigerators working with Gd reach values of 60% of the theoretical limit, comparated to only about 40% in the best gas-compression refrigerators. However, one of the majors obstacles for the use of that technology in large scale is the utilization of high pure Gd metal (99,99% wt.) to produce the Gd-Ge-Si alloys, as the impurity elements decrease the intensity of the magnetocaloric effect (EMC). In this work, we prove that annealling of the Gd 5Ge 2Si 2 can promote remarkable values for the EMC, comparated to that obtained for the alloy with high pure Gd. Also, the as cast alloy and the annealed alloy are not monophasic, but have at least two crystalline phases into its microstructure. Results for the optical and electronic microscopy and magnetization measurements are reported.
Rights: fechado
Identifier DOI: 
Date Issue: 2003
Appears in Collections:Unicamp - Artigos e Outros Documentos

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