Enhanced Magnetocaloric Properties of the (MnNi)<sub>0.6</sub>Si<sub>0.62</sub>(FeCo)<sub>0.4</sub>Ge<sub>0.38</sub> High-Entropy Alloy Obtained by Co Substitution
oleh: Zhigang Zheng, Pengyan Huang, Xinglin Chen, Hongyu Wang, Shan Da, Gang Wang, Zhaoguo Qiu, Dechang Zeng
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2024-09-01 |
Deskripsi
In order to improve the magnetocaloric properties of MnNiSi-based alloys, a new type of high-entropy magnetocaloric alloy was constructed. In this work, Mn<sub>0.6</sub>Ni<sub>1−</sub><i><sub>x</sub></i>Si<sub>0.62</sub>Fe<sub>0.4</sub>Co<i><sub>x</sub></i>Ge<sub>0.38</sub> (<i>x</i> = 0.4, 0.45, and 0.5) are found to exhibit magnetostructural first-order phase transitions from high-temperature Ni<sub>2</sub>In-type phases to low-temperature TiNiSi-type phases so that the alloys can achieve giant magnetocaloric effects. We investigate why <i>c<sub>hexagonal</sub></i>/<i>a<sub>hexagonal</sub></i> (<i>c<sub>hexa</sub></i>/<i>a<sub>hexa</sub></i>) gradually increases upon Co substitution, while phase transition temperature (<i>T<sub>tr</sub></i>) and isothermal magnetic entropy change (Δ<i>S<sub>M</sub></i>) tend to gradually decrease. In particular, the <i>x</i> = 0.4 alloy with remarkable magnetocaloric properties is obtained by tuning Co/Ni, which shows a giant entropy change of 48.5 J∙kg<sup>−1</sup>K<sup>−1</sup> at 309 K for 5 T and an adiabatic temperature change (Δ<i>T<sub>ad</sub></i>) of 8.6 K at 306.5 K. Moreover, the <i>x</i> = 0.55 HEA shows great hardness and compressive strength with values of 552 HV2 and 267 MPa, respectively, indicating that the mechanical properties undergo an effective enhancement. The large Δ<i>S<sub>M</sub></i> and Δ<i>T<sub>ad</sub></i> may enable the MnNiSi-based HEAs to become a potential commercialized magnetocaloric material.