Preparation method of micrometer grade NiMnCa magnetic memory alloy grain

Abstract

The invention involves a preparation method of NiMnGa magnetic memory alloy micron-scale particles. The invention uses planetary ball grinder, prepares micron-scale Ni48-55Mn24-30Ga20-25(at.%) magnetic memory alloy particles through controlling size of abrading-ball, ball-material rate, ball grinder rotary speed and ball grinding time and adding proper organic adjuvant, the particle size is controlled less than 100 microns, the particles has complete same phase-change behavior and crystal morphology with body material. The component of prepared NiMnGa magnetic memory alloy micron-scale particles using the invention is uniform, signal martensite phase and iron magnetic properties can be prepared just after short time heat treatment, the art is simple and the preparation time is short. The micron-scale NiMnGa magnetic memory alloy particles can be both raw material for preparing NiMnGa composite and a granular magnetic refrigerating material.

Description

technical field [0001] The invention relates to a method for preparing NiMnGa magnetic memory alloy micron-scale particles. Background technique [0002] NiMnGa magnetic memory alloy is a new type of memory material developed in recent years. It can undergo martensitic twin transformation reorientation or magnetic field-induced martensitic transformation under the action of an external magnetic field to generate large reversible strains, overcoming the Traditional memory alloys have the disadvantages of slow response speed and small reversible strain of electrostrictive and magnetostrictive materials. Studies have shown that NiMnGa single crystal can obtain a magnetically induced strain close to 10%, and the response rate can reach the KHz level. NiMnGa magnetic shape memory alloy is currently the only ferromagnetic Heusler alloy with thermoelastic martensitic phase transition, so that NiMnGa alloy can be used as both temperature sensor and magnetic field sensor. However, ...

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Problems solved by technology

At present, although there have been reports on NiMnGa particle-reinforced resin intelligent composite materials, all of them are to explain its performance and structure, but there are few reports on the preparation of the key NiMnGa alloy particles.

The article "Magnetocaloric effect in NiMnGa particles produced by spark erosion" published by Y.J.Tang et al. in the United States in the Journal of Applied Physics in 2005 uses spark corrosion to prepare NiMnGa alloy particles, the particle size is less than 100 microns, and the particle shape is close to spherical , but there are the following disadvantages: (1) There are many internal defects in the alloy particles, and a single martensitic phase and ferromagnetism need to be heat-treated at high temperature for a long time to obtain a single martensitic phase and ferromagnetism; (2) There are many disordered parent phases inside the particles, and The composition between the particles is uneven; (3) a special pulse power supply is required, and the power is large and the power consumption is large

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