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.