Change on Tetragonality of L10 Phase With Homogenization Time on Ni50Mn29Sb21 Shape Memory Heusler Alloy

In this study, the effects of homogenization heat treatment on microstructural and magnetic properties of the Ni 50 Mn 29 Sb 21 shape memory Heusler alloy was investigated. Ni–Mn–Sb alloy system may be an important candidate to contribute on magnetic shape memory literatüre for practical applications. Based on the results of X-ray diffraction investigations, the B2 → Θ (L1 0 ) structural phase change was detected. Vibrating sample magnetometer and differential scanning calorimetry experiments revealed that the alloy exhibits a ferromagnetic transition as well as a thermoelastic martensitic transformation. At the same time, the B2 type bcc lattice structure of the paramagnetic phase has been established. A narrow temperature hysteresis has been discovered in the structural β (B2) → Θ (L1 0 ) diffusionless martensitic phase transformation. The average lattice parameter of the B2 phase was calculated to be 2.942 Å. According to measurements taken between 41 and 47 deg, the thick 110 B2 reflection was separated into two peaks: 110 B2 and 111 L10 . Diffraction peaks demonstrate the occurrence of L1 0 martensite phase close to 110 B2 habit plane borders. All these findings were supported by scattering electron microscope and metal microscopy analyses.