Magnetoelastic properties in polycrystalline ferromagnetic shape memory Heusler alloys

Structural Change in Ni-Fe-Ga Magnetic Shape Memory Alloys after Severe Plastic Deformation

“…It is well-known that in Ni-Fe-Ga-based alloys with Ga ≤ 27 at%, the composition has a typical β + ɤ two phase zone. In addition, the ɤ (FCC) second phase is considered responsible for the improved ductility of these alloys [7,10]. The effect of deformation of the matrix and phase precipitates is clearly manifested in the microstructure.…”

“…Buttons of Ni-Fe-Ga, Ni-Co-Fe-Ga, and Ni-Co-Fe-Ga-Al alloys were prepared by arc melting in argon using high-purity elements (99.99%) in appropriate proportion. The experimental procedure for preparing the bulk alloys and effect of substitutions on the structure and magnetic properties was described in detail earlier [7]. The bulk Ni-Fe-Ga-based alloy (with and without Co and Al substitution) was subjected to SPD so as to improve mechanical properties, as well as plasticity.…”

“…In fact, the shape memory effect and superelasticity underlie the fast response, reversible, and repeatable operation. Some of the most promising MSMA are Heusler-type ferromagnetic SMAs [6,7]. Heusler alloys are intermetallic compounds with the stoichiometry X 2 YZ, where X and Y represent transition metals and Z elements are from groups III, IV, or V [8].…”

“…Ni-Mn-Ga alloys are known to exhibit large magnetic field-induced strain and, thus, recommended as rapid magnetic actuators [5], but they are very brittle and difficult to shape [3]. Ni-Fe-Ga Heusler alloys are suitable for industrial applications avoiding brittleness, one of the major drawbacks of the Ni-Mn-Ga system [7]. The microstructure in this system is strongly dependent on the chemical composition and thermo-mechanical history since they influence both Tc and martensitic transformation temperatures [7,10].…”

“…Ni-Fe-Ga Heusler alloys are suitable for industrial applications avoiding brittleness, one of the major drawbacks of the Ni-Mn-Ga system [7]. The microstructure in this system is strongly dependent on the chemical composition and thermo-mechanical history since they influence both Tc and martensitic transformation temperatures [7,10]. For superior mechanical properties, including high strength and hardness together with increased fatigue resistance, originally coarse-grained alloys can be substantially refined down to nanometric structures [11].…”