Gallium alloys are ideal base carriers for temperature-sensitive ferrofluids, which can be used for energy convection, soft robotics, microchannels, magnetorheological devices, etc. In this study, gallium was mixed with different substances (In, Sn, Zn, Ge, and Al) to obtain a low melting point, reduce the wetness and adhesion of its alloys, and realize low viscosity. The melting point, contact angle on certain solid plates, viscosity, and viscoelasticity of the gallium alloys were measured, and some useful gallium alloys were obtained. The experimental results showed that Ga₈₀In₁₀Sn₁₀ had lower wettability at a larger contact angle of 148.6° on the Teflon plate. Here, (Ga₈₀In₁₀Sn₁₀)₉₇Zn₃ with a melting point of 8.2 °C, lower than the melting point of Galinstan, was developed. It had a viscosity about three times that of water at room temperature and an elastic response from 0.1 to 100 Hz at a 1% strain amplitude for the viscoelasticity. It was expected that a kind of temperature-sensitive magnetic fluid with a gallium-based liquid alloy as the base carrier liquid would be prepared in the future with Teflon as the container to achieve energy conversion under the drive of the magnetic field.

Herein, fine magnetic particles with high saturation magnetization and a large temperature-sensitive magnetization in the temperature range 300–400 K were prepared for use in temperature-sensitive magnetorheological fluids (MRF). Two methods, namely high-energy ball milling (HEBM) and sintering followed by HEBM to produce mechanochemical alloys, were used to produce R 2_Fe17 component particles. The prepared particles were submicron- to micron-sized and contained rare-earth–iron alloys and α-Fe phases. Among the prepared particles, Sm ₂ Fe ₁₇ composition powder exhibited the highest temperature sensitivity of −0.02 A m ² kg ⁻¹ K ⁻¹ at 400 K. Furthermore, powders with varying Fe and Sm composition ratios were prepared by sintering and ball milling. The powder prepared from the initial SmFe ₅ composition exhibited the highest temperature sensitivity of −0.32 A m ² kg ⁻¹ K ⁻¹ at 400 K and saturation magnetization was ∼90 A m ² kg ⁻¹ . The powder was composed of SmFe ₅ and Sm ₂ Fe ₁₇ in crystalline, α-Fe phase and amorphous phase, as revealed by X-ray diffraction analysis (XRD) and scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM) with the selected area electron diffraction (SAED).