Magnetic Field-Induced reverse martensitic transformation and thermal transformation arrest phenomenon of Ni₄₁Co₉Mn₃₉Sb₁₁ alloy

In order to investigate behavior of magnetic field-induced reverse martensitic transformation for Ni-Co-Mn-Sb, magnetization experiments up to a static magnetic field of 18 T and a pulsed magnetic field of 40 T were carried out. In the thermomagnetization curves for Ni₄₁Co₉Mn₃₉Sb₁₁ alloy, the equilibrium transformation temperature T₀ was observed to decrease with increasing applied magnetic field,_μ0H, at a rate of dT₀/d_μ0H = 4.6 K/T. The estimated value of entropy change evaluated from the Clausius-Clapeyron relation was about14.1 J/(K·kg), which was in good agreement with the value obtained by differential scanning calorimetric measurements. For the isothermal magnetization curves, metamagnetic behavior associated with the magnetic field-induced martensitic transformation was observed. The equilibrium magnetic field,_μ0H₀ = (_μ0H_Af +_μ0H_Ms)/2, of the martensitic transformation tended to be saturated at lower temperature; that is, transformation arrest phenomenon was confirmed for the Ni-Co-Mn-Sb system, analogous with the Ni(Co)-Mn-Z (Z = In, Sn, Ga, Al) alloys. Temperature dependence of the magnetic field hysteresis,_μ0H_hys =_μ0H_Af −_μ0H_Ms, was analyzed based on the model for the plastic deformation introduced by the dislocations. The behavior can be explained by the model and the difference of the sweeping rate of the applied magnetic field was well reflected by the experimental results.