The high-temperature hydrogenation behavior of LaFe11.6Si1.4 and splitting of LaFe11.6Si1.4Hy magnetocaloric transition

Zheng, Hongyan; Tang, Yongbai; Chen, Yungui; Wu, Jianghong; Wang, Huasheng; Xue, Xiao; Wang, Jing; Pang, Wenkai

doi:10.1016/j.jallcom.2015.05.164

Cited by 16 publications

(3 citation statements)

References 31 publications

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“…This segregation reveals itself macroscopically as a separation of a single well-defined first order transformation into two distinct first order transformations at different temperatures after repeated cycling [29]. However, the original single transformation behavior can be easily recovered by short time annealing around 450 K [30] where the homogenized hydrogen distribution is again recovered.…”

Section: Introductionmentioning

confidence: 98%

Dynamic re-equilibration controlled multi-step transformations in (Mn, Fe)₂(P, Si) alloys

Brown¹,

Chen²,

Braham³

et al. 2020

J. Phys. D: Appl. Phys.

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In (Mn, Fe) 2 (P, Si) alloys crystallographic first-order phase transformations enable strong coupling of magnetic and entropic properties, potentially leading to high-efficiency energy generation and refrigeration applications. Although hysteresis losses that limit these applications can be reduced through careful control of alloy composition, compositional tuning can also unfavorably influence transformation temperatures and magnetocaloric coupling strength. Hence, exploration of additional processing variables enabling independent control of transformation properties is crucial. In this work, we investigate the role of thermal history as an additional processing variable, exploiting thermally-activated mechanisms to control properties of non-diffusive transformations in (Mn, Fe) 2 (P, Si) alloys. In so doing, we report an unusual transformation-splitting phenomenon following annealing at intermediate times, where a single well-defined magneto-structural transformation evolves towards a multi-step transformation with individual steps occurring at multiple distinct temperatures. On longer annealing at the same temperatures, single-step transformation behavior is recovered. Through additional magnetic and crystallographic characterization, we show that the thermal history-controlled multi-step behavior results from sluggish thermally-activated diffusion. The two-step transformation corresponds to non-equilibrium bimodal composition distributions in the transforming phase, and these develop through a dynamic re-equilibration process as the alloy passes relatively slowly between different thermal equilibria. Together, these results suggest that thermal history primarily controls the transformation properties of (Mn, Fe) 2 (P, Si) alloys indirectly through the composition of one or more transforming phases. Additional investigations are needed to develop thermal history processing for decoupling hysteresis control from other transformation properties.

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Section: Introductionmentioning

confidence: 98%

Dynamic re-equilibration controlled multi-step transformations in (Mn, Fe)₂(P, Si) alloys

Brown¹,

Chen²,

Braham³

et al. 2020

J. Phys. D: Appl. Phys.

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“…T C can be raised from ~200 K to room temperature or even higher by addition of interstitial atoms like H [23,[25][26][27]. Hydrogenation of LaFe 13−x Si x is the most effective method to shift T C to room temperature while maintaining a large magnetocaloric effect [28]. Quaternary La(Fe,Co,Si) 13 compounds can increase T C and change the magnetic transition from first-order to second-order, accompanied by lower MCE.…”

Section: Introductionmentioning

confidence: 99%

One-Step Sintering Process for the Production of Magnetocaloric La(Fe,Si)13-Based Composites

Zhong

Dong

Huang

et al. 2022

Metals

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A one-step sintering process was developed to produce magnetocaloric La(Fe,Si)13/Ce-Co composites. The effects of Ce2Co7 content and sintering time on the relevant phase transformations were determined. Following sintering at 1373 K/30 MPa for 1–6 h, the NaZn13-type (La,Ce)(Fe,Co,Si)13 phase formed, the mass fraction of α-Fe phase reduced and the CeFe7-type (La,Ce)(Fe,Co,Si)7 phase appeared. The mass fraction of the (La,Ce)(Fe,Co,Si)7 phase increased, and the α-Fe phase content decreased with increasing Ce2Co7 content. However, the mass fraction of the (La,Ce)(Fe,Co,Si)7 phase reduced with increasing sintering time. The EDS results showed a difference in concentration between Co and Ce at the interphase boundary between the 1:13 phase and the 1:7 phase, indicating that the diffusion mode of Ce is reaction diffusion, while that of Co is the usual vacancy mechanism. Interestingly, almost 100 % single phase (La,Ce)(Fe,Co,Si)13 was obtained by appropriate Ce2Co7 addition. After 6 h sintering at 1373 K, the Ce and Co content in the (La,Ce)(Fe,Co,Si)13 phase increased for larger Ce2Co7 content. Therefore, the Curie temperature increased from 212 K (binder-free sample) to 331 K (15 wt.% Ce2Co7 sample). The maximum magnetic entropy change (−∆SM)max decreased from 8.8 (binder-free sample) to 6.0 J/kg∙K (15 wt.% Ce2Co7 sample) under 5 T field. High values of compressive strength (σbc)max of up to 450 MPa and high thermal conductivity (λ) of up to 7.5 W/m∙K were obtained. A feasible route to produce high quality La(Fe,Si)13 based magnetocaloric composites with large MCE, good mechanical properties, attractive thermal conductivity and tunable TC by a one-step sintering process has been demonstrated.

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“…Magnetic refrigerator research indicates, the La(Fe x Si 1-x ) 13 -based compound with the itinerant-electron metamagnetic (IEM) transition is a kind of magnetic refrigeration material with very promising practicability [1][2][3][4][5][6]. But lower Curie temperature of La(Fe x Si 1-x ) 13 makes it difficult to be used in domestic and high temperature appliances.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Absorption of LaFe10.9Co0.8Si1.3 Compound under Low Hydrogen Gas Pressure

Fu¹,

Han²

2017

dtetr

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The effects of hydrogen absorption on structure, Curie temperature and phase transition property for the LaFe 10.9 Co 0.8 Si 1.3 compound are investigated by X-ray diffraction (XRD) and differential scanning calorimeter (DSC) in a 1-atm H 2 gas. The original compound and hydride present cubic NaZn 13 -type structure. The Curie temperature of LaFe 10.9 Co 0.8 Si 1.3 shifts from 277K to 346K and temperature range of the phase transition becomes wider significantly after hydrogen absorption.

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The high-temperature hydrogenation behavior of LaFe11.6Si1.4 and splitting of LaFe11.6Si1.4Hy magnetocaloric transition

Cited by 16 publications

References 31 publications

Dynamic re-equilibration controlled multi-step transformations in (Mn, Fe)₂(P, Si) alloys

Dynamic re-equilibration controlled multi-step transformations in (Mn, Fe)₂(P, Si) alloys

One-Step Sintering Process for the Production of Magnetocaloric La(Fe,Si)13-Based Composites

Hydrogen Absorption of LaFe10.9Co0.8Si1.3 Compound under Low Hydrogen Gas Pressure

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The high-temperature hydrogenation behavior of LaFe11.6Si1.4 and splitting of LaFe11.6Si1.4Hy magnetocaloric transition

Cited by 16 publications

References 31 publications

Dynamic re-equilibration controlled multi-step transformations in (Mn, Fe)2(P, Si) alloys

Dynamic re-equilibration controlled multi-step transformations in (Mn, Fe)2(P, Si) alloys

One-Step Sintering Process for the Production of Magnetocaloric La(Fe,Si)13-Based Composites

Hydrogen Absorption of LaFe10.9Co0.8Si1.3 Compound under Low Hydrogen Gas Pressure

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Dynamic re-equilibration controlled multi-step transformations in (Mn, Fe)₂(P, Si) alloys

Dynamic re-equilibration controlled multi-step transformations in (Mn, Fe)₂(P, Si) alloys