Method for synthesizing arbitrarily shaped NiTi shape memory alloy in situ

Abstract

The invention discloses a method for synthesizing an arbitrarily shaped NiTi shape memory alloy in situ. The method comprises the following steps of: uniformly mixing pure Ti powder and pure Ni powder with the grain size of less than 50 mu m and the same mean grain size according to an approximate equiatomic proportion, and preconfiguring mixed powder layers with the thickness of 10 to 20 mu m on a pure Ti metal substrate layer by layer by utilizing a selective laser melting rapid prototyping method; and melting mixed powder point by point, line by line and layer by layer by utilizing a continuous YAG or a fiber laser with the focusing spot diameter of less than or equal to 40 mu m under the protection condition of the water and oxygen content of less than 10 ppm, and finishing the in-situ synthesis and the melting stacking processing of the NiTi shape memory alloy in a designed shape. The invention can overcome the difficulties of the prior art, and provides the method with short cycle, low cost, high flexibility, and capacity of synthesizing the arbitrarily shaped NiTi shape memory alloy with the consistency of near 100 percent and without composition segregation and impurities.

Description

technical field [0001] The invention belongs to the field of nickel-titanium shape-memory alloys, and in particular relates to a method for rapidly synthesizing nickel-titanium shape-memory alloys by a selective laser melting technique. Background technique [0002] Nearly equal atomic ratio NiTi shape memory alloys have stable shape memory effect and superelastic function, as well as excellent strength, wear resistance, corrosion resistance and biocompatibility, etc., in industrial automation, aerospace, medical and health, It has wide application prospects in the fields of instrumentation and machinery manufacturing. [0003] Due to the high melting point and remarkable work hardening characteristics of NiTi alloy, its preparation technology and parts processing have been paid much attention. At present, there are two methods for the preparation of NiTi shape memory alloys. One is the melting and casting method: the bulk raw materials of Ni and Ti are first melted into in...

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Problems solved by technology

The synthesis of NiTi shape memory alloy by powder metallurgy is a kind of in-situ synthesis. One of the biggest difficulties in the above synthesis method is that it is difficult to accurately control the formation and reaction speed of reactants everywhere, and there are significant differences in the synthesis from the surface to the inside of the billet. ; At the same time, due to the long sintering time, it is difficult to suppress the reaction generation of the mesophase and the epigenetic phase, which will have an adverse effect on the performance of the material, resulting in many shortcomings as mentioned above