A kind of preparation method of memory alloy nano lamination ni/ti preform

Abstract

A method for preparing a memory alloy nano-laminated Ni / Ti preform belongs to the technical field of functional composite materials. The preparation steps include: (1) material preparation, (2) packaging, (3) rolling; the present invention adopts room temperature accumulation Overlap rolling, combined with wrapping to limit and hinder deformation, is conducive to the coordinated deformation of Ni / Ti, and solves the problems that NiTi alloy is easy to introduce impurity elements in the traditional smelting process, resulting in poor material processing performance, large deformation resistance during cold processing, and small deformation in each pass. ; Since the three-stage cumulative rolling is carried out at room temperature, and the intermediate process has not been annealed, the residual stress of the Ni / Ti layered preform after the final composite is large, the activity between the Ni atom and the Ti atom interface is high, and the layered Ni / Ti preform has high hardness and high modulus of elasticity. The shorter the time required for Ni and Ti to react and diffuse to form a NiTi shape memory alloy at a certain temperature, the NiTi alloy grains can be refined to a certain extent, and a high-quality NiTi shape memory alloy can be obtained. The finer the grains, the more The stability of the phase transition temperature can be improved, and the austenitizing phase transition temperature will also increase slightly.

Description

technical field [0001] The invention belongs to the technical field of functional composite materials, in particular to a method for preparing a memory alloy nano-laminated Ni / Ti preform. Background technique [0002] NiTi shape memory alloy is a functional composite material, which is widely used in aerospace, biomedical, energy and chemical industries, etc. It not only has high specific strength, good wear resistance and corrosion resistance, high fatigue strength, but also has shape memory Effect (SME) and superelasticity (SE), as well as good biocompatibility and other advantages. At present, the commonly used method for preparing NiTi shape memory alloys is mainly to obtain NiTi alloy ingots by smelting, and then control the microstructure by subsequent hot or cold processing of the ingots, so that they have shape memory properties. However, the hot processing method in the prior art has harsh process conditions, and it is easy to cause surface and even internal oxidat...

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Problems solved by technology

[0003] In order to solve the problems of element pollution in the NiTi alloy ingot obtained by the traditional smelting method, large deformation resistance in the cold working process, small pass deformation, low material plasticity, and complicated process, the present invention provides a memory alloy nano-laminated Ni / Ti prefabricated The preparation method of the billet is to prepare the laminated Ni / Ti preform by using the three-stage cumulative rolling large plastic deformation technology, combined with the cold working method to refine the grains, increase the specific surface interface of titanium and nickel grains, and reduce the layer thickness. The distance between the layer and the layer, as the grain size decreases, the atomic activity is enhanced, and the titanium atoms and nickel atoms are fully reacted and diffused at a certain temperature and time, which promotes their rapid alloying

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