Enhanced magnetocaloric effect in Ni-Mn-Sn-Co alloys with two successive magnetostructural transformations

Abstract

High magnetocaloric refrigeration performance requires large magnetic entropy change ΔSM and broad working temperature span ΔTFWHM. A fourth element doping of Co in ternary Ni-Mn-Sn alloy may significantly enhance the saturation magnetization of the alloy and thus enhance the ΔSM. Here, the effects of Co-doping on the martensite transformation, magnetic properties and magnetocaloric effects (MCE) of quaternary Ni47−xMn43Sn10Cox (x = 0, 6, 11) alloys were investigated. The martensite transformation temperatures decrease while austenite Curie point increases with Co content increasing to x = 6 and 11, thus broadening the temperature window for a high magnetization austenite (13.5, 91.7 and 109.1 A·m2/kg for x = 0, 6 and 11, respectively). Two successive magnetostructural transformations (A → 10 M and A → 10 M + 6 M) occur in the alloy x = 6, which are responsible for the giant magnetic entropy change ΔSM = 29.5 J/kg·K, wide working temperature span ΔTFWHM = 14 K and large effective refrigeration capacity RCeff = 232 J/kg under a magnetic field of 5.0 T. These results suggest that Ni40.6Mn43.3Sn10.0Co6.1 alloy may act as a potential solid-state magnetic refrigerant working at room temperature.

The Effect of Different Atomic Substitution at Mn Site on Magnetocaloric Effect in Ni50Mn35Co2Sn13 Alloy

“…As one of the typical Ni-Mn-Z Heusler alloys, Ni-Mn-Sn alloy undergoes a martensitic transformation from ferromagnetic (FM) austenite to weak-magnetic martensite, which is accompanied with an abrupt change of magnetization ∆M [6]. This large ∆M across martensitic transformation results in a high difference of Zeeman energy E zeeman = µ 0 H∆M, which drives a metamagnetic transition from the weak-magnetic martensite to FM austenite, thus leading to a large MCE [5,7]. Therefore, it is desirable to enhance the ∆M during martensitic transformation in order to obtain a large MCE.…”

MAGNETOCALORIC EFFECT AROUND CURIE TEMPERATURE IN Ni50-x CuxMn38Sn12B3 SHAPE MEMORY RIBBONS

“…The magnetization difference, , between two phases is responsible for magnetic entropy change [27]. If one wants to improve , the magnetization difference should be tuned.…”

“…The area between magnetization and demagnetization curves gives HL. The can be calculated by subtracting hysteresis loss from , = − [27]. The calculated hysteresis areas at 335 K for the x=0, 1 and 3 were very small and found to be 0.59, 0.66 and 1.05 J/kg for the x=0 ,1 and 3, respectively.…”

Optimizing the Caloric Properties of Cu-Doped Ni–Mn–Ga Alloys

“…As has been emphasized before, ECE and MCE are both direct, and thus can be simultaneously to improve the overall refrigeration capability of the studied alloy, although simultaneous use of both caloric effects is not equally advantageous for all working conditions. values of ΔSM are among the highest for Heusler-type FSMAs, especially if we focus on mate displaying direct MCE [28][29][30][31][32], and are consistent with reported values for similar compositio either polycrystalline [20] and single crystalline samples [33]. Regarding the ECE, the obtained va of Δ SE, significantly lower than those of ΔSM, are also large compared with those obtained for o Heusler alloys [32][33][34][35] It's worth mentioning that, according to Figure 9-and as explained above-application of a 2 T field would promote a maximum transformed fraction of 0.4; similarly, a gross extrapolation to 100 MPa of Figure 10d would yield a maximum entropy between 35% and 40% of the limit value.…”