Enhancing the magnetocaloric response of high-entropy metallic-glass by microstructural control

Abstract

Non-equiatomic high-entropy alloys (HEAs), the second-generation multi-phase HEAs, have been recently reported with outstanding properties that surpass the typical limits of conventional alloys and/or the first-generation equiatomic single-phase HEAs. For magnetocaloric HEAs, non-equiatomic (Gd36Tb20Co20Al24)100−xFex microwires, with Curie temperatures up to 108 K, overcome the typical low temperature limit of rare-earth-containing HEAs (which typically concentrate lower than around 60 K). For alloys with x = 2 and 3, they possess some nanocrystals, though very minor, which offers a widening in the Curie temperature distribution. In this work, we further optimize the magnetocaloric responses of x = 3 microwires by microstructural control using the current annealing technique. With this processing method, the precipitation of nanocrystals within the amorphous matrix leads to a phase compositional difference in the microwires. The multi-phase character leads to challenges in rescaling the magnetocaloric curves, which is overcome by using two reference temperatures during the scaling procedure. The phase composition difference increases with increasing current density, whereby within a certain range, the working temperature span broadens and simultaneously offers relative cooling power values that are at least 2-fold larger than many reported conventional magnetocaloric alloys, both single amorphous phase or multi-phase character (amorphous and nanocrystalline). Among the amorphous rare-earth-containing HEAs, our work increases the working temperature beyond the typical <60 K limit while maintaining a comparable magnetocaloric effect. This demonstrates that microstructural control is a feasible way, in addition to appropriate compositional design selection, to optimize the magnetocaloric effect of HEAs.

Review on magnetocaloric high-entropy alloys: Design and analysis methods

“…In addition, exponent n as a function of temperature has been used for identifying the presence of multiphases in Gd-Tb-Co-Al-Fe HEAs [21,67]. The authors found broadened widths in the minima of n(T) curves for their samples, which attribute to the observed enhancement in the refrigerant capacity values.…”

(Magneto)Transport Properties of (TiZrNbNi)1−xCux and (TiZrNbCu)1−xCox Complex Amorphous Alloys

“…Furthermore, their excellent mechanical properties and phase stability in a large temperature range makes them interesting for technological application, such as magneto-caloric devices [ 15 ] and antidiffusion and anticorosive coatings (see, for example, [ 16 ] for a review). Continuing our work on multicomponent compositionally complex metal alloys [ 17 , 18 , 19 , 20 , 21 , 22 ], we report here on the results of a systematic study of electronic properties (the electrical resistivity, superconductive transitions and Hall effect) on amorphous samples of two quinary TE-TL alloy systems and (from hereon and , respectively).…”

Magnetic properties and promising magnetocaloric performances in the antiferromagnetic GdFe2Si2 compound

“…The magnitudes of the MC effect have a strong correlation with the corresponding magnetic phase transition (MPT); therefore, the investigation of the MC effects of magnetic materials can provide considerable valuable information for the better understanding of MPT [5][6][7][8][9]. Therefore, many magnetic materials have been synthesized and systematically determined with regard to the magnetic proper-ties, MPT, and MC performances not only to search for suitable candidates for active MR application at cryogenic and near room temperature but also to better understand the MPT of magnetic materials [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. However, a large gap still exists at the present stage between the practical MR application requirements and the performances of known MC materials.…”

“…In the last several decades, investigations have been performed on the MPT and MC effects in the rare-earth (RE)-based materials in amorphous and crystallized states owing to the large magnetic moments of RE ions, which result in considerable MC effects [18][19][20][21][22][23][24][25]. Law and Franco [13] reviewed the MC performances in RE-based high-entropy alloys.…”