Method and equipment for improving shape memory alloy superelasticity
A memory alloy and superelasticity technology, applied in the field of memory alloy heat treatment and aging, can solve the problems of long time, serious surface oxidation, large energy consumption, etc., and achieve the effect of promoting vacancies, accelerating atomic diffusion and the formation of secondary phases.
Inactive Publication Date: 2015-06-03
SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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[0004] In order to improve the superelasticity of TiNi memory alloys and avoid the problems of large energy consumption, long time and serious surface oxidation in the existing heat treatment furnace heating and aging treatment process, the present invention provides a method and equipment for improving the superelasticity of shape memory alloys. The pulse current is directly introduced into the cold-rolled or solid-solution state memory alloy wire and strip, and kept for a long time. This aging treatment process makes TiNi memory alloys get better results than ordinary heating furnace treatment and direct current heating treatment. , so that the memory alloy can obtain higher superelasticity
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[0035] The TiNi memory alloy specimen to be processed is a TiNi wire with a diameter of 2.20 mm, and the composition is Ti 49.2 Ni 50.8 , was cold-worked into a strip with a thickness of 1.24 mm and a width of 2.78 mm; the strip was cut into a 200 mm-long specimen, and then the two ends were respectively fixed on the connecting clip, and the pulse current was introduced into the specimen through the connecting clip .
[0036] Referring to the experimental setup figure 2 , and each part is respectively connecting clamp 1, tension spring 2, high-energy pulse power supply 3, and TiNi memory alloy specimen 4. The TiNi memory alloy test piece 4 is connected to the output end of the high-energy pulse power supply 3 through two connecting clips 1, and the outer ends of the two connecting clips are respectively provided with a tension spring 2, and the TiNi memory alloy test piece 4 is applied 30 The tensile force of ~60N makes the TiNi memory alloy specimen 4 in a flat state.
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Abstract
A method for improving shape memory alloy superelasticity comprises the following steps: leading impulse current into a memory alloy piece to heat the memory alloy, enabling the memory alloy piece to be stable at a balancing temperature finally, and keeping for 2 to 150 min at the balancing temperature to carry out an aging treatment. The memory alloy piece can be switched in high energy impulse current through two connecting clamps; the memory alloy sample piece is imposed with certain drawing force by springs through the two connecting clamps; the memory alloy is enabled to keep flat and straight. Compared with heat-treatment furnace heating and direct current direct heating aging treatment, the method can enable the adjusting effect of the interior tissue structure of the material to be better, so that the memory alloy superelasticity can be enabled to be optimal, and through the stretching deformation with 8% strain, the minimum residual strain is only 0.11 %.
Description
technical field [0001] The invention relates to heat treatment aging technology of memory alloys, specifically a method and equipment for improving the superelasticity of shape memory alloys. The high-energy electric pulse current is directly introduced into memory alloy parts, heated to an appropriate temperature by its own resistance, and kept for a certain period of time for aging treatment. , so that the superelasticity of TiNi memory alloy is improved. Background technique [0002] Using direct current or high-energy continuous pulse current to directly heat the workpiece to process metal materials, both of which realize heating through the resistance of the material itself, provide atomic diffusion activation energy, and make the structure and properties of the metal material change. High-energy continuous electric pulse is a new type of power source developed in recent years. It can be widely used in electrical treatment, electroplastic processing, powder sintering, ...
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IPC IPC(8): C22F3/00
Inventor 唐国翌祝儒飞宋国林谢子豪
Owner SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV