Search

The magnetostriction curves and minor loops of the TbDyFe [110] oriented crystal are tested under different compressive pre-stress from 0 to 120 MPa. It is observed that the magnetostriction hysteresis first increases from about 33 Oe under 0 MPa, achieves the maximum of about 70 Oe under 30 MPa, and then decreases to about 16 Oe under 120 MPa (near disappearance) with an increase in the compressive pre-stress. By the theoretical simulation, it is found that upon increasing the compressive pre-stress the dominant energy changes from magnetocrystalline anisotropy energy to magnetoelastic energy. This leads to the domain rotation mode changing from irreversibility to reversibility and consequently results in the decrease of magnetostriction hysteresis, which explains the experimental results very well.

The magnetostriction curve of [110]-oriented Tb0.3Dy0.7Fe1.9 crystal is measured under different compressive prestress. It is observed that the saturation magnetostriction keeps on increasing with the increase in compressive prestress from 0 to 75 MPa. The distribution of the free energy within the (110) plane normal to the stress axis is calculated to clarify the enhancement of saturation magnetostriction under large compressive prestress. It is found that with the increase in the prestress, the lowest energy positions deviate from the initial four ⟨111⟩ easy axes in the (110) plane, approaching the [11¯0] and [1¯10] orientations. The stress-induced anisotropy results in the change in initial domain configuration and further the enhancement of saturation magnetostriction, which well explains the experimental results.

Seeking high precision actuator and transducer materials potentially applied under high load remains active in recent years. Magnetostrictive property, magnetostriction saturation field HS, and pizeomagnetic coefficient d33 are investigated in Fe81Ga19 alloy under high compressive prestress. The measured saturation magnetostriction remains above 300 ppm in the ⟨001⟩ oriented Fe81Ga19 polycrystalline rod under high compressive prestress up to 431 MPa. Two-stage phenomenon was observed in curves plotted for HS and d33 against compressive prestress σ. The domain rotation path and magnetostriction under different compressive prestress are simulated, and this helps to deeply understand the tested magnetostriction. Based on the simulation, the mathematical equations of HS-σ and d33-σ were established for Fe–Ga ⟨001⟩ oriented crystal revealed two mechanisms, which satisfy proposed functions of experimental data. The high magnetostriction and low saturation field under high prestress indicate that Fe–Ga alloy is ...