[en] The Nd₁₃Fe₇₉Ga₁B₇ alloy powders were treated by the HDDR process under different reduced hydrogen pressures in the range 0.2-0.8 bar, and the effects of the reduced hydrogen pressure on magnetic properties of the HDDR-treated alloy powders were investigated. It was found that the HDDR-treated alloy powders exhibit a considerable anisotropy in addition to an appropriate coercivity. As the reduced hydrogen pressure is lowered, the degree of anisotropy decreases significantly, whereas the intrinsic coercivity increases. The largest anisotropy of up to 1.62 is achieved in the powders HDDR-treated under a reduced hydrogen pressure of 0.8 bar, and the highest coercivity of 724 kAm^-1 is attained in the powders HDDR-treated under 0.4 bar. (orig.)

[en] The micro soft robot which mimics the movement of microorganisms is one of the important research directions in the field of robotics. This study proposes a programmable 3D printing method for magnetically driven micro soft robots based on surface tension. High-performance surfactant was used to reduce the surface free energy of the printing substrate, so that the liquid printing material can maintain a stable shape under the effect of surface tension. Pre-printed auxiliary lines with ultraviolet curing adhesive made the subsequently printed silicone maintain its shape defined by the auxiliary lines in the plane, and the thickness of its shape was adjusted by controlling the total amount of silicone. Silicone mixed with and without neodymium–iron–boron powder was printed into different areas successively, which eventually combined into a magnetically driven micro soft robot with a specific two-dimensional structure. Magnetically driven motion experiments confirmed that micro soft robots with different driving modes can be manufactured by this 3D printing method, and the influences of printing parameters as well as magnetically driven parameters on the motion performance of the microrobots are studied. (paper)