Magnetocaloric Composite Materials

Law, Jia Yan; Franco, V.

doi:10.1016/b978-0-12-819724-0.00038-0

Cited by 12 publications

(10 citation statements)

References 80 publications

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“…[3] contains details of the various discontinuous measurement protocols for performing magnetization measurements to determine for the MCE appropriate for both types of magnetocaloric materials. For reviews on magnetocalorics, one can refer to recent comprehensive reports on materials [4][5][6] and devices [7].…”

Section: Invited Feature Paper-reviewmentioning

confidence: 99%

“…In the case of composites, deviations from the universal curve become more apparent when phase fractions or the MCE responses of the several coexisting phases are similar (for further details on magnetocaloric composite materials, readers can refer to ref. [5]). Recently, a phase deconvolution procedure based on universal scaling of the MCE has been successfully applied to a biphasic SOPTs composite for predicting the response of the pure constituent phases [62] and then further extended to deconvolute SOPT from FOPT in a Heuser alloy [63].…”

Section: Temperature Averaged Entropy Changementioning

confidence: 99%

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

Law

Franco

2022

Journal of Materials Research

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The search for high-performance functional alloys with improved service life and reliability entails the optimization of their mechanical properties. Recently, the high-entropy alloy (HEA) design concept has found new alloys with excellent mechanical properties. It utilizes multiprincipal elements to yield high configurational entropy of mixing, entailing a large compositional freedom with wide window of opportunities for property exploration. Their functional properties are usually modest when compared to conventional materials. The discovery of HEAs with optimal combination of mechanical and functional properties would be a leap forward in the reliability of functional devices. This review article focuses on magnetocaloric HEAs, the design approaches, and the appropriate analysis methods for their performance. We will highlight the efficient strategic search within the vast HEA space, which has been instrumental for significantly enhancing MCE performance, closing the pre-existing gap between magnetocaloric HEAs and high-performance conventional magnetocaloric materials. Outlook for future directions will also be included. Graphical abstract

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Section: Invited Feature Paper-reviewmentioning

confidence: 99%

Section: Temperature Averaged Entropy Changementioning

confidence: 99%

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

Law

Franco

2022

Journal of Materials Research

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“…Thus, for all of the abovementioned chemical modifications, the decrease in the ∆T ad value was due to the blurring of the magnetic transition and lower magnetic entropy. For some composites, an enhancement of the magnetocaloric properties was observed [79]. Therefore, we calculated the magnetic entropy change for an exemplary composite according to the equation: ∆Sm comp (T) = (1 − z)∆Sm I (T) + z∆Sm II (T), where ∆Sm I (T) and ∆Sm II (T) represent the experimental data for the composite components.…”

Section: Alloymentioning

confidence: 99%

“…In Table 5, the values of the ordering temperature (TC), the maximum entropy change (|∆Sm| MAX ), and the relative cooling power (RCP) for a magnetic field change of 1 T and 2 T are collected. We chose the |∆Sm| MAX and RCP values for a field changes of 1 T and 2 T because they are most often presented in the publications and For some composites, an enhancement of the magnetocaloric properties was observed [79]. Therefore, we calculated the magnetic entropy change for an exemplary composite according to the equation: ∆S m comp (T) = (1 − z)∆S m I (T) + z∆S m II (T), where ∆S m I (T) and ∆S m II (T) represent the experimental data for the composite components.…”

Section: Alloymentioning

confidence: 99%

Tuning of the Magnetocaloric Properties of Mn5Ge3 Compound by Chemical Modification

et al. 2022

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The rare earth-free Mn5Ge3 compound shows magnetocaloric properties similar to those of pure Gd; therefore, it is a good candidate for magnetic refrigeration technology. In this work, we investigate the influence of chemical substitution on the crystal structure and the magnetic, thermodynamic, and magnetocaloric properties of a polycrystalline Mn5Ge3 compound prepared by induction melting. For this purpose, we replaced 5% of the Mn with Cr or Co and 5% of the Ge with B or Al. The additional chemical elements were shown not to change the crystal structure of the parent compound (space group P63/mcm, No. 193). In the case of the magnetic properties, all samples remained ferromagnetic with the ordering temperature (TC) lower than for the original compound (TC = 295(1) K). The exception was the sample with B, where we observed an increase in TC by 3 K. The maximum value of the magnetic entropy change, |∆Sm|MAX (for a magnetic field change of 5 T), decreased from 7.1(1) for Mn5Ge3 to 6.2(1), 6.8(1), 4.8(1), and 5.8(1) J kg−1 K−1 for the alloys with B, Al, Cr, and Co, respectively. The adiabatic temperature change (∆Tad) (for a magnetic field change of 1 T) was determined from the specific heat measurements and was equal to 1.1(1), 1.2(1), 1.2(1), 0.8(1), and 0.8(1) K for Mn5Ge3, Mn5Ge2.85B0.15, Mn5Ge2.85Al0.15, Mn4.75Cr0.25Ge3, and Mn4.75Co0.25Ge3, respectively. The obtained data were compared with those from the literature. It was found that the substitution allowed for tuning of the ordering temperature in a wide temperature range. At the same time, the reduction in the magnetocaloric parameters’ values was relatively small. Therefore, the produced Mn5Ge3-based alloys allow for the expansion of the operation temperature range of the parent compound as a magnetocaloric material.

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“…Furthermore, the appearance of some nanocrystals leads to minor compositional difference between the amorphous matrix and nanocrystalline phase, leading to the widening of the T C distribution and improving the relative cooling power (RCP) by 7%. MCE enhancement is found for conventional alloys exhibiting amorphous/nanocrystalline dual-phase structures [6, [30][31][32][33][34][35], whereby those Gd-based compositions show an improve-ment of up to ~84% and ~21% in the values of maximum magnetic entropy change ( S M max ) and refrigeration capacity (RC) (for 5 T), respectively. In particular, a very recent report by Feng et al…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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.

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Magnetocaloric Composite Materials

Cited by 12 publications

References 80 publications

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

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

Tuning of the Magnetocaloric Properties of Mn5Ge3 Compound by Chemical Modification

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

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