Enhancement of the magnetic refrigerant capacity in partially amorphous Fe70Zr30 powders obtained by mechanical alloying

Effect of α-Fe impurities on the field dependence of magnetocaloric response in LaFe11.5Si1.5

“…Table 1. Along with the fcc La(FeSi) 13 phase, bcc Fe-type phase appears with (200) texture in the melt-spun sample. Small traces of LaFeSi cannot be discarded.…”

“…This scientific interest rose up especially after the works of Gschneidner Jr. and Pecharsky, who found giant MCE in Gd 5 Si 2 Ge 2 compound at 292 K [1]. Since then other systems, such as Heusler alloys [2], La(FeSi) 13 H d [3] or MnAs [4] compounds and previously FeRh [5], were found to exhibit a giant MCE too [6,7]. In general, giant MCE is associated to a first order phase transition implying structural or itinerant electron metamagnetic transitions.…”

“…In the particular case of La(Fe,Si) 13 family, Si stabilizes the NaZn 13 -type phase (space group Fm3c) but the production of pure single phase samples is tricky and requires long high temperature annealing that can be reduced if the precursor alloy is well homogenized by rapid quenching [8] or milling [9]. The typical residual impurity phases are ferromagnetic bcc Fe and tetragonal weak Pauli paramagnetic LaFeSi intermetallic [10].…”

Analysis of the Magnetocaloric Effect in Powder Samples Obtained by Ball Milling

“…Among RE-based materials Gd 5 Si 2 Ge 2 , [13,14] La(FeSi) 13 , [15][16][17][18] RE 2 Fe 17 intermetallics, [19,20] clathrates Eu 8 Ga 16 Ge 30 , [21] and amorphous alloys [13,14,22] can be found. Among TM-based systems Heusler alloys, [23][24][25] MnAs, [26][27][28][29] cFeNi, [30][31][32] and amorphous alloys [33][34][35][36][37] can be found. A general difference found in BM samples regarding their MCE with respect to that of bulk counterparts is a decrease of the DS M peak but a temperature broadening of the MCE response, which can lead to an enhancement of the refrigerant cooling power.…”

“…In particular cases, the presence of intermetallics with suitable Curie temperatures can lead to an enhancement of MCE. [35] For Fe-based amorphous alloys obtained by rapid quenching, subsequent ball milling produces an increase in the metal-metal distance enhancing the magnetism of the system. [36] However, extended milling can deteriorate the MCE signal when the phase responsible for it is destroyed, as it occurs for Gd 5 Si 1.8 Ge 1.8 Sn 0.4 system, for which an amorphous phase is formed.…”