Study On Glass Forming Ability And Magnetocaloric Properties Of GdNiCo Ternary Amorphous Alloys

Gd-based amorphous alloys have a wide range of applications in the field of magnetic refrigeration because of their excellent glass forming ability(GFA)and magneto-caloric effect(MCE).This paper mainly investigates the effect of adding different content of Co on glass forming ability,magnetic properties and magnetic entropy behavior of a Gd65Ni35 amorphous alloy,and builds the table-like MCE of Gd65Ni35-xCox amorphous composite.The specific work is as follows:The Gd65Ni35 amorphous alloy was selected as a base component by using the λn criterion and the γm*criterion.Gd65Ni35-xCox(x=5,10,15,20,25)as-spun ribbons were prepared and subjected to X-ray Diffraction(XRD)test and Differential Scanning Calorimeter(DSC)test.The experimental data were used to calculate the glass forming ability criterion such as the reduced glass transition temperature(Trg),γ criterion,γm criterion and et al.The results show that a small addition of Co(x=5,10)is beneficial to improve the glass forming ability of Gd65Ni35 amorphous ribbon.When x=15,20 of Gd65Ni35-xCox as-spun ribbons,there is no significant change in the glass forming ability,and when x=25 of Gd65Ni35-xCox as-spun ribbon,the ribbon is not completely amorphous structure.The magnetic properties of Gd65Ni35-xCox(x=0,5,10,15,20)amorphous ribbons were tested by Physical Property Measurement System(PPMS).magnetic properties and magnetocaloric properties of the Gd65Ni35-xCox amorphous ribbonss were investigated.The results show that the Curie temperature of the alloys increase linearly with the increase of Co content,and the peak of magnetic entropy of the alloys increase with the increase of Co content when x is less than 20,which is due to the enhancement of 3d-3d direct exchange effect and excess magnetic entropy via the addition of Co.;Gd65Ni35-xCox(x=0,5,10,15,20)amorphous ribbons are standard soft magnetic materials with the refrigeration capacity of 750 J/kg(5 T)above and the full width at half maximum of 80 K(5 T)above.The magnetic entropy behavior of the alloys was studied.The results show that the dependence of the magnetic entropy peak of Gd65Ni35-xCox alloys on the magnetic field can be described by the expression-ΔSm∝Hn.We attempted to construct a table-like MCE curve of Gd65Ni35-xCox amorphous composite.The magneto-caloric properties of the material were significantly improved after the construction,the highest value of the full width at half maximum increased by 3 5%,the maximum cooling capacity increased by 10%.The maximum Ericsson cycle temperature is close to 30 K after alloying,and the effective cooling capacity(RCeff)is close to 220 J/kg(5 T).Therefore,it is possible to design a magnetic refrigeration material that is more in line with the Ericsso cycle,and lay the foundation for the subsequent research of Gd-TM(other element)alloys.