The magnetocaloric effect of melt spun GdAlFeM (M=Tb, Dy, Ho, Er, Ge and Mn) ribbons

• Main Authors: Hsiang-chun Chen, 陳翔竣
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/77114451436081266161

碩士 === 國立中正大學 === 物理所 === 98 === Recently, there have been increasing interests in the magnetocaloric effect (MCE) of amorphous materials. Extensive researches were focused on the Gd-based series alloys. Accordingly, in the study, the effect of different elements substitution for Gd and Al on Gd65Al15Fe20 alloy ribbons was investigated. At first, we chose the Gd65Al15Fe20 as the base alloy and studied the effect of Ge and Mn substitution for Al on the MCE of melt spun Gd65Fe20Al15-xMx (M = Ge and Mn; x = 0-7) ribbons. The results showed that the Curie temperature was increased with the addition of Ge and Mn. For Ge substituted Gd65Fe20Al15-xGex ribbons, with increasing the Ge content, the Curie temperature increased from 213 K for x = 0 to 235 K for x = 7, while the ΔSM decreased from 1.32 J/kg K for x = 0 to 0.84 J/kg K for x = 7. In Gd65Fe20Al15-xMnx ribbons, with increasing the Mn concentration, the Curie temperature increased from 213 K for x = 0 to 223 K for x = 7. The optimal MCE was appeared in Gd65Fe20Al12Mn3 ribbon, while the change of the magnetic entropy, ΔSM , of it was 1.39 J/kg K. Furthermore, the substitution for Al by the fourth elements like Ge and Mn were not increased the ΔSM effectively, therefore, we studied the effect of different heavy rare earth elements substitution for Gd on the MCE of Gd65-xRExAl15Fe20 (RE = Tb, Dy, Ho and Er; x = 0-20) ribbons. All of them were found that the Curie temperature decreased, while ΔSM increased with increasing RE concentration. The optimal MCE was in Gd65-xErxAl15Fe20 ribbons, ΔSM increased from 1.32 J/kg K for x = 0 to 1.77 J/kg K for x = 20, Curie temperature decreased from 213 K for x = 0 to 152 K for x = 20, and show that the RE addition had the effect in raising the ΔSM of the alloy ribbons.