Influence of Fe substitution on thermal stability and magnetocaloric effect of Gd60Co40-Fe amorphous alloy

Observation of a Broadened Magnetocaloric Effect in Partially Crystallized Gd60Co40 Amorphous Alloy

“…We found that the maximum magnetic entropy change of Gd 60 Co 40 amorphous alloy (8.3 J•kg −1 •K −1 [17]) was higher than that of Gd 55 Co 35 Ni 10 (6.5 J•kg −1 •K −1 [15]) and Gd 55 Co 35 Mn 10 (6.47 J•kg −1 •K −1 [14]) amorphous counterparts with analogous Curie temperature (T C ). Additionally, according to the Gd-Co binary phase diagram [27], the constituent phases of Gd 60 Co 40 alloy after equilibrium solidification are Gd 4 Co 3 and Gd 12 Co 7 types.…”

“…From the magnified image of the 210-230 K part on dM/dT-T curves (displayed in the inset of Figure 2b), there is a weak peak for 513 K/20 min annealed ribbon, which reveals first magnetic phase transition at 219 K correlated to the magnetic transition of the Gd4Co3 phase (TC = 220 K) [21]. Its second magnetic transition obtained at 196 K is sharp and associated with the amorphous ferrimagnetic phase (TC = 193 K) [17], which is in good agreement with the microstructure consisted by slight amount of crystallites and predominant amorphous matrix, as discussed in Section 3.1. Owing to the analogous microstructure of the 513 K/40 min and 513 K/60 min annealed samples, their multi-magnetic transition behaviors are similar to each other and three transitions can be observed at temperatures 174 K/194 K/219 K and 176 K/195 K/219 K. Compared with the magnetic transition behavior in the 513 K/20 min annealed sample, an extra transition related to the Gd12Co7 crystalline (TC = 160.8 K) appeared [36].…”

“…From the magnified image of the 210-230 K part on dM/dT-T curves (displayed in the inset of Figure 2b), there is a weak peak for 513 K/20 min annealed ribbon, which reveals first magnetic phase transition at 219 K correlated to the magnetic transition of the Gd 4 Co 3 phase (T C = 220 K) [21]. Its second magnetic transition obtained at 196 K is sharp and associated with the amorphous ferrimagnetic phase (T C = 193 K) [17], which is in good agreement with the microstructure consisted by slight amount of crystallites and predominant amorphous matrix, as discussed in Section 3.1.…”

“…Additionally, according to the Gd-Co binary phase diagram [27], the constituent phases of Gd 60 Co 40 alloy after equilibrium solidification are Gd 4 Co 3 and Gd 12 Co 7 types. The T C of crystalline Gd 4 Co 3 , Gd 12 Co 7 and amorphous Gd 60 Co 40 are 220 K [21], 179 K [22] and 193 K [17], respectively, and the intervals between different T C are suitable for achieving the table-like MCE [28,29]. To reveal whether the partially crystallized Gd 60 Co 40 alloy ribbon will exhibit enhanced table-like or broadened MCE, in this study, the influence of crystallization treatment on the structure, magnetic and magnetocaloric properties of Gd 60 Co 40 melt-spun ribbons was investigated.…”

“…Gd-TM (TM = Co, Fe, Ni, and Mn) amorphous alloys with near-room temperature MCE have attracted more attention in recent years. Generally, the broadened |∆S M |-T profile can be observed in these materials, owing to the highly disordered structure of amorphous systems, which smears out the magnetic transition [1,11,15,[17][18][19][20][21][22][23][24][25][26]. In-situ crystallization treatment of the amorphous ribbons is also utilized to obtain multi-phase magnetic refrigerant, such as crystallized Gd 55 Co 35 Ni 10 ribbon containing Gd 4 (Co, Ni) 3 and Gd 12 (Co, Ni) 7 phases, and partially crystallized Gd 55 Co 35 Mn 10 with precipitation of the Gd 3 Co-type and Gd 12 Co 7 -type phases in the amorphous matrix, both of them possess broadened table-like MCE [14,15].…”