Enhanced magnetocaloric and mechanical properties of melt-extracted Gd55Al25Co20 micro-fibers

• High-quality Gd55Al25Co20 metallic glass magnetocalorific fibers were melt-extracted.
• They show superior MCE performance versus its counterpart in BMGs.
• They have tensile strength of 1189 MPa and high security threshold of 796 MPa.
• The excellent performances result from size effect and amorphous structure.

We report rapidly quenched Gd-based metallic glass micro-fibers with a nominal composition of Gd55Al25Co20, which are fabricated by melt-extraction method, and possess remarkable magnetic properties and excellent mechanical performances. Attractively, these metallic glass micro-fibers exhibit a noticeable and reversible magnetocaloric effect (MCE). For a magnetic field change of 5 T, the isothermal magnetic entropy change (−ΔSm) reaches as high as 9.7 J kg−1 K−1 and the refrigerant capacity (RC) achieves a relatively large value of 652 J kg−1. In addition, the Arrott plots indicate that the ferromagnetic-paramagnetic transition is of second-order. Remarkably, the average value of maximum tensile strength for Gd55Al25Co20 metallic glass micro-fibers is statistically calculated to be 1189 MPa and their fracture reliabilities were characterized using Weibull and lognormal methods, respectively. It is demonstrated that the as-extracted metallic glass micro-fibers have an excellent fracture modulus of 19.9 and a high security threshold of 796 MPa for practical application. Though with a low Curie temperature, the adaptability and outstanding characteristics of the melt-extracted Gd-based metallic glass micro-fibers are expected to be applied in the multifunctional fields of MCE-based refrigeration.