Study On Glass Forming Ability And Magnetocaloric Properties Of GdCoFe-(B,Si) Amorphous Alloys

Magnetic refrigeration(MR)has attracted increasing interest due to its advantages of environmental safety and higher efficiency.Ericsson refrigeration cycle is a thermodynamic cycle which is suitable for MR near room temperature,and the efficient Ericsson cycle requires that magnetic entropy change(?SM)is a constant.Therefore,it is very important to find materials with a table-like magnetocaloric effect.Gd-Co-Fe amorphous alloys exhibit an excellent magnetic and magnetocaloric properties near room temperature.In this work,the glass forming ability(GFA)and magnetocaloric properties of the GdCoFe-(B,Si)alloys were analyzed and discussed.Furthermore,the mechanism of the performance was discussed from the microscopic perspective.In this study,according to the deep eutectic criterion,Inoue empirical criterion,and equiatomic substitution,the Gd50Co50-xFex(x=0,5,10,15,20,25)alloys were designed based on the binary Gd50Co50 amorphous alloy.The alloy ribbons were prepared by single roller rapid cooling method.The samples obtained under a spinning speed of 50 m/s were confirmed to be amorphous alloys through the measurements of XRD and DSC.Moreover,the crystallization activation energy(Ec)of the samples was calculated and utilized to investigate crystallization behavior and thermal stability of the alloys.It was revealed that with increasing Fe content,the Ec of the Gd50Co50-xFex(x=0,5 and 10)increased,while it decreased for x=15,20 and 25.Therefore,the addition of moderate amount of Fe element can improve the thermostability of the alloys.The sample of Gd50Co40Fe10 amorphous alloy shows the highest GFA among the alloys.The data of magnetic properties of the samples were collected by a physical property measurement system.The magnetic transition temperature(TC)of Gd50Co50-xFex(x=0,5,7,10)amorphous alloys,which were obtained from the temperature dependence of the magnetization curves,increases with the increasing content of Fe substitution.Under the magnetic field of 5 T,the table-like magnetocaloric effect was observed in both Gd50Co43Fe7 and Gd50Co40Fe10 amorphous alloys,and the value of |?SM| were 3.14±0.16 J/(kg·K)and 2.76±0.14 J/(kg·K)in the temperature range of 230?305 K and 210?315 K individually.Besides,for the Gd50Co43Fe7 and Gd50Co40Fe10 amorphous alloys,the Tpk,corresponding temperature of |?SMpk|,shifts to the lower temperature with increasing applied field changes,which means the substitution of Fe for Co enhances the antiferromagnetic or speromagnetic interaction in the Fe sublattice and then leads to the magnetic nature of the alloys varied from collinear ferrimagnetism to sperimagnetism.By adding metalloid elements B and Si to the Gd50Co40Fe10 alloy,the Tpk shifts to lower temperature with increasing magnetic field can be modified,and the |?SMpk|increases from 1.28 J/(kg·K)to 2.04 J/(kg·K)under applied filed of 2 T.However,the Tc decreases.Additionally,the value of n(Tpk)derived from the equation of |?SM|?Hn becomes closer to the theoretical value of the amorphous alloy.A nearly linear relation between |?SM| and TC-2/3 can be observed.