American scientists combined modern materials science with ancient smelting technology to develop a new cobalt-iron alloy, which has good magnetostriction, does not require the use of rare earth elements and is easy to produce, and is expected to be used to manufacture magnetic field-controlled sensors And micromechanical equipment.
The new cobalt-iron alloy has huge magnetostriction. The ferromagnetic substance will grow or shrink in size under the action of an external magnetic field. After removing the external magnetic field, it will return to its original length. This phenomenon is called the magnetostrictive effect. The use of ferromagnets with strong magnetostriction is very wide, for example, they can be used to manufacture sensitive magnetic field detectors and slim actuators in micromechanical equipment (mainly used to manufacture micrometer sensors and micrometer motors on silicon wafers), and Magnetostrictive devices do not require wires and can be controlled by external magnetic fields.
In order to discover the best metal mixing ratios and processing procedures, the scientific research team led by Ichiro Takeuchi, a scientist at the University of Maryland, manufactured hundreds of tiny test cantilevers, which are 10 mm long silicon beams that look like diving boards. The researchers wrapped it in a thin layer of alloy and slowly changed the ratio of cobalt and iron throughout the cantilever array. Two different heat treatment methods were used throughout the process: the alloy was first heated to the highest temperature and then suddenly quenched in water. Quenching is a traditional metallurgical technique that can solidify the microstructure of a material in a specific state.
Measurements by the National Institute of Standards and Technology (NIST) and Stanford Synchrotron Radiation Light Source (SSRL) show that the new cobalt-iron alloy can exhibit a huge magnetostrictive effect in a magnetic field of 0.01 Tesla. The new alloy has a delicate and heterogeneous nano-scale structure in which cobalt-rich crystals are embedded through different iron-rich crystal structures. Ichiro Takeuchi said that the magnetostriction effect of the new alloy is a little worse than that of the best magnetostrictive material available-terbium dysprosium iron alloy composed of rare earth elements, but its advantage lies in not using rare earth elements.
NIST's materials scientist Will Osborne said that compared with ordinary piezoelectric micro-devices, magnetostrictive devices have attracted more and more scientists' attention because they are easier to operate on a smaller level. Piezoelectric crystals are usually oxides, they are fragile, often made of lead, and difficult to manufacture; while the latest magnetostrictive alloys are made of metal and are more easily compatible with current equipment manufacturing methods, they are the next generation of manufacturing Ideal material for micromechanical equipment.
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