Experimental Study on the Magnetomechanical Characteristics of Ni-Mn-Ga Ferromagnetic Shape Memory Alloy Single Crystals

Ferromagnetic shape memory alloys: Alternatives to Ni–Mn–Ga

This paper intends to review the state-of-the-art in the field of ferromagnetic shape memory alloys different than Ni–Mn–Ga, developed in the ast years. It starts with the effects of additions of different fourth elements to Ni–Mn–Ga and continues with the review of other Heusler (or B2) i-based and Co-based alloy systems, like Ni–Mn–X, Ni–Fe–Ga, Co–Ni–Al and Co–Ni–Ga alloys. Finally, ferromagn...

Magnetomechanical properties of a high-temperature Ni–Mn–Ga magnetic shape memory actuator material

A Ni–Mn–Ga single crystal with a phase transformation temperature above 350 K is investigated. The material demonstrates a magnetic field-induced strain (MFIS) of 7% at room temperature and of 4.2% at 350 K. The temperature dependence of the magnetic anisotropy and of the saturation magnetization has been studied in detail. At 350 K a maximum magnetic stress of 1.6 MPa and a twinning stress of ...

Magnetocrystalline Anisotropy in a Single Crystal Fe–Ni–Ga Ferromagnetic Shape Memory Alloy*

In order to discuss the advent of the magnetic-field-induced strains for a single crystal Fe22:0Ni51:5Ga26:5 shape memory alloy, the magnetic easy axis in the 14M martensite phase and the magnetocrystalline anisotropy constant K have been investigated. From the data on the spontaneous thermal expansion and the magnetization curves, the magnetic easy axis of the 14M martensite phase was determin...

Experimental investigations on the nanomechanical properties of sputter deposited Ni-Mn-Ga ferromagnetic shape memory thin films

NiMnGa thin films were dc magnetron sputter deposited onto well cleaned substrates of Si(100) and glass in high pure argon environment of vacuum 0.01 mbar at low sputtering power of 36W and their mechanical properties were investigated by nanoindentation technique using calibrated Berkovich indenter. Results reveal that the films posses elasto-plastic nature. The elastic modulus of the films wa...

Direct evidence of detwinning in polycrystalline Ni-Mn-Ga ferromagnetic shape memory alloys during deformation

Elastic constants of Ni-Mn-Ga magnetic shape memory alloys

We have measured the adiabatic second order elastic constants of two Ni-Mn-Ga magnetic shape memory crystals with different martensitic transition temperatures, using ultrasonic methods. The temperature dependence of the elastic constants has been followed across the ferromagnetic transition and down to the martensitic transition temperature. Within experimental errors no noticeable change in a...