The effect of mechanical stress on Ni63.8Mn11.1Ga25.1 microwire crystalline structure and properties

• Preparation of NiMnGa Heusler-type microwires.
• Effect of the presence of glass coating on the structure of Heusler alloy microwires.
• Discussions of the internal stresses effect on structure of NiMnGa microwires.
• Discussions of the internal stresses effect on properties of NiMnGa microwires.

We studied structure and magnetic properties of Heusler alloy microwires. The dependence of the phase composition of the annealed microwires on the presence of glass coating has been found. The crystalline structure of the glass-coated samples is composed of two cubic crystalline phases of different density. The samples annealed without coating are in the single-phase state. The two-phase state is supposed to be caused by intrinsic stresses resulted from the action of opposite sign stresses in different microwire sections. The magnetic properties of the fabricated Heusler-type microwires differ from their bulk and thin film counterparts. Annealing of microwires considerably affect magnetic properties at room temperature. Unusual magnetic behavior is connected with two-phase structure of microwires.