Two different heat treatments have been carried out on similar Mn1−xNi1−xFe2xSi0.95Al0.05 compositions with magnetostructural transitions between hexagonal and orthorhombic crystal structures around room temperature. The samples were analyzed concerning their structural, microstructural, magnetic, and caloric properties. The results show that the introduction of a high-temperature step, before the heat treatment (1073 K/7 days) usually used in the literature for such compounds modifies the microstructure, leading to sharper transitions with shorter transition widths, and stronger latent heat peaks. Magnetic field-assisted calorimetry and vibrating sample magnetometry provide methods to assess the effect of magnetic field on the broad transitions for the sample with x = 0.32 and the sharp transitions seen in the sample with x = 0.31.
