Effect of heat treatment procedure on magnetic and magnetocaloric properties of Ni₄₃Mn₄₆In₁₁ melt spun ribbons

Realization of Enhanced Refrigeration Capacity with Non-Hysteretic Behavior in Ni40Gd5Co5Mn37In12Si1 Alloy Near Room Temperature at 2T

“…With increase in annealing time, the traces of the low-temperature martensite phase in Ni 45 Co 5 Mn 37 In 12 Si 1 (NM) get disappeared, especially for the annealing time of 10 h, as seen in Figure S1a, Supporting Information, and the cubic L2 1 austenite phase gets strongly stabilized. From Figure S1a (refer, Supporting Information), it is clear that heat treatment significantly stabilizes the austenite phase at room temperature, which strongly influences the MCE of Ni–Co–Mn–In–Si alloys, and the results were consistent with the previous reports. − ,, …”

“…When Gd is substituted at the Ni site in Ni–Co–Mn–In–Si alloy, the phase fraction of the L2 1 -type structure increases to ∼92.6%, whereas the phase fraction of the L2 1 structure in GS is raised to ∼94.1; however, Gd-added samples show the second phases of GdMn 12 as well. Furthermore, the lattice parameters of NM, GS, and GA were calculated as 5.9723(5), 6.0196(8), and 6.0272(7) Å, respectively, and they indicate that lattice parameters increase even in Gd-added samples, due to occupation of Gd either at the Ni site or Mn site which are consistent with previous reports. − The details of Rietveld refinement of NM, GS, and GA samples are summarized in Supporting Information, Table S1.…”

“…From Figure S1a (refer, Supporting Information), it is clear that heat treatment significantly stabilizes the austenite phase at room temperature, which strongly influences the MCE of Ni−Co−Mn−In−Si alloys, and the results were consistent with the previous reports. [36][37][38][39][40][41][42][43]49,50 Interestingly, the L2 1 structure of Ni−Co−Mn−In−Si alloy has been significantly stabilized only upon Gd substitution at the Ni site, as seen in Figure 1b without any further heat treatment. Additionally, the addition of Gd in the Ni 45 Co 5 Mn 37 In 12 Si 1 has also played a major role on suppression of the low-temperature martensite phase and enhances the peak intensity of the high-temperature austenite phase, as seen in Figure 1c.…”

“…To be specific, pure elemental Gd has regarded to be a state-of-the-art material that exhibits the maximum RC of ∼402 at 5 T near SOPT with non-hysteretic characteristics near room temperature . Furthermore, Pecharsky and Gschneidner have also reported the giant MCE in the intermetallic alloy of Gd 5 Si 2 Ge 2 with the RC of 640 J kg –1 and Δ S M of ∼9.4 J kg –1 K –1 under 5 T which is notably high as compared to elemental Gd. , Particularly, a few class of materials exhibits high MCE in the FOPT region with large RC values and distinguishable hysteretic nature, such as Gd 5 Si 2 Ge 2 , LaFe 13– x Si x H, MnFeP 0.45 As 0.55 , MnAs 1– x Sb x , Co 50 Ni 22 Ga 2 , and Ni–Mn-based Heusler alloys, − whereas some group of materials show notably good RC values in the SOPT region with almost non distinguishable thermal hysteretic character such as Gd 60 Fe 20 Al 20 , EuTiO 3 , Pr 0.7 Ca 0.3 Mn 0.95 Cr 0.05 O 3 , and so on. However, most of materials that show large MC response near SOPT in the proximity of the room-temperature range are either expensive or low-abundant which indeed limits their practical applications.…”

Impact of annealing on martensitic transformation of Mn50Ni42.5Sn7.5 shape memory alloy

“…After annealing, the alloy is subjected to a relaxation of the structure, which can slightly modify the site of the atom, causing in the change of the Mn-Mn distance. Finally, another justification for this change is the dependence between the annealing and grain size for annealed alloys observed in micrographs [20][21][22]. Glezer et al [22] investigated the correlation between martensitic transition temperatures and grain size in Fe-Ni-B alloys.…”