The magnetic phase transition and magnetocaloric effects of Gd65(Cu,Co,Mn)35 amorphous ribbons were investigated. The increased Mn substitution for Co or Mn substitution for Cu led into a higher secondorder magnetic p...The magnetic phase transition and magnetocaloric effects of Gd65(Cu,Co,Mn)35 amorphous ribbons were investigated. The increased Mn substitution for Co or Mn substitution for Cu led into a higher secondorder magnetic phase transformation temperature, near 200 K in all ribbons. Under the field change of 7T, a maximum entropy change(Sm max) of 6 J kg^-1K^-1 was achieved in Gd(65)Cu10Co20Mn5 ribbon and slightly dependent on the compositions. With varied composition, a full width at half of Sm maxwas greatly widened to be over than 180 K for Gd65Cu15Co10Mn(10) ribbon. The refrigeration capacity was also greatly enhanced to 1000J kg^-1 for Gd65Cu20Co10Mn5 ribbon, which was even excellent compared with other Gd-based amorphous systems.展开更多
Gd-based bulk metallic glass has drawn strong attention because of its large magnetic entropy changes. Thermal stability of metallic glass is a very important issue for its application. In the paper, crystallization b...Gd-based bulk metallic glass has drawn strong attention because of its large magnetic entropy changes. Thermal stability of metallic glass is a very important issue for its application. In the paper, crystallization behavior of Gd53Al24Co20Zr3 bulk metallic glass was investigated using non-isothermal differential scanning calorimetric （DSC） technique. Attention was given to the analytic details. The crystallized volume fractions as a function of temperature were derived from the DSC signals, where heat capacity change between amorphous phase and crystalline phase was considered. The local activation energies at different crystallized volume fraction were estimated using Doyle-Ozawa and Agrawal methods. The results suggested that the Doyle-Ozawa equation was appropriate to get local activation energy due to its simplicity and accuracy. The local activation energy depended on the crystallized volume fraction. Function reflecting crystallization mechanism was also deduced. The crystallization mechanism of the Gd-based bulk metallic glass was discussed.展开更多
基金supported financailly by the National Natural Science Foundation of China (Nos. 51674082, 51771049 and 51790484)
文摘The magnetic phase transition and magnetocaloric effects of Gd65(Cu,Co,Mn)35 amorphous ribbons were investigated. The increased Mn substitution for Co or Mn substitution for Cu led into a higher secondorder magnetic phase transformation temperature, near 200 K in all ribbons. Under the field change of 7T, a maximum entropy change(Sm max) of 6 J kg^-1K^-1 was achieved in Gd(65)Cu10Co20Mn5 ribbon and slightly dependent on the compositions. With varied composition, a full width at half of Sm maxwas greatly widened to be over than 180 K for Gd65Cu15Co10Mn(10) ribbon. The refrigeration capacity was also greatly enhanced to 1000J kg^-1 for Gd65Cu20Co10Mn5 ribbon, which was even excellent compared with other Gd-based amorphous systems.
基金Project supported by the Fundamental Research Funds for the Central University (N100409001 and N090209001)
文摘Gd-based bulk metallic glass has drawn strong attention because of its large magnetic entropy changes. Thermal stability of metallic glass is a very important issue for its application. In the paper, crystallization behavior of Gd53Al24Co20Zr3 bulk metallic glass was investigated using non-isothermal differential scanning calorimetric （DSC） technique. Attention was given to the analytic details. The crystallized volume fractions as a function of temperature were derived from the DSC signals, where heat capacity change between amorphous phase and crystalline phase was considered. The local activation energies at different crystallized volume fraction were estimated using Doyle-Ozawa and Agrawal methods. The results suggested that the Doyle-Ozawa equation was appropriate to get local activation energy due to its simplicity and accuracy. The local activation energy depended on the crystallized volume fraction. Function reflecting crystallization mechanism was also deduced. The crystallization mechanism of the Gd-based bulk metallic glass was discussed.
