Tailored martensitic transformation and enhanced magnetocaloric effect in all-d-metal Ni₃₅Co₁₅Mn₃₃Fe₂Ti₁₅ alloy ribbons

Abstract

The crystal structure, martensitic transformation and magnetocaloric effect have been studied in all-d-metal Ni35Co15Mn33Fe2Ti15 alloy ribbons with different wheel speeds (15 m/s (S15), 30 m/s (S30), and 45 m/s (S45)). All three ribbons crystalize in B2-ordered structure at room temperature with crystal constants of 5.893(2) Å, 5.898(4) Å and 5.898(6) Å, respectively. With the increase of wheel speed, the martensitic transformation temperature decreases from 230 K to 210 K, the Curie temperature increases slightly from 371 K to 378 K. At the same time, magnetic entropy change (ΔS m) is also enhanced, as well as refrigeration capacity (RC). The maximum ΔS m of 15.6(39.7) J/kgK and RC of 85.5(212.7) J/kg under ΔH = 20(50) kOe appear in S45. The results indicate that the ribbons could be the candidate for solid-state magnetic refrigeration materials.

Magnetostructural Transformation and Magnetocaloric Properties of (Ni37.5Co12.5Mn35Ti15)100−xBx (x = 0.0 and 0.4) Melt-Spun Ribbons

“…However, the patterns for the B-doped samples correspond to a pure B2-type austenite since, as Figure 3a shows, the martensitic transformation appeared below room temperature. In earlier reports, austenite showed a B2-type crystal structure [12,17,18,27]. The lattice parameters were determined using the equation = and = • + + −…”

“…Alloying elements, such as Fe [17], Cu [16,18,19], V [20], Cr [21], and B [12,22], have been added to Ni-Co-Mn-Ti alloys to tune the temperature of the structural transition or to improve the mechanical and magnetocaloric properties. Due to its small atomic radio and depending on the amount added, B is an element that may occupy interstitial or substitutional sites in Heusler-type Ni-Mn-X alloys [23][24][25][26].…”