Method for synthesizing arbitrarily shaped NiTi shape memory alloy in situ

A memory alloy, in-situ synthesis technology, applied in the field of nickel-titanium shape memory alloys, can solve the problem of synthesis differences, adverse effects of material properties, and difficulty in suppressing intermediate equivalence, and achieve the effect of ensuring uniformity

Active Publication Date: 2010-12-01
TECH LASER TECH SHANGHAI CO LTD
3 Cites 14 Cited by

AI-Extracted Technical Summary

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...
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Method used

[0064] The present invention can take into account the in-situ synthesis of NiTi shape memory alloys and the manufacture of NiTi alloy parts with complex shapes, solving the high-quality NiTi shape memory alloy synthesis and processing problems of parts. The specific embodiment of the present invention is not limite...
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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.

Technology Topic

Short cycleRapid prototyping +12

Examples

  • Experimental program(5)

Example Embodiment

[0024] Example 1:
[0025] A method for directly preparing NiTi shape memory alloys of arbitrary shapes from element powders, including the following steps:
[0026] (1) Powder preparation: use pure Ni powder and pure Ti powder with a particle size of less than 50μm and the same average particle size as raw materials, and mix uniformly according to the Ni/Ti atomic ratio of 51:49;
[0027] (2) Use selective laser melting rapid prototyping method to prepare NiTi shape memory alloy of arbitrary shape:
[0028] (2.1) The mixed powder with the atomic ratio of Ni/Ti of 51:49 is used as the raw material, continuous YAG or fiber laser is used as the energy source, the focal spot diameter is 40μm, and the titanium plate is used as the forming substrate to form any three-dimensional The graphic STL file is input to the SLM rapid prototyping equipment, which is layered and discretized by the slice software to generate the laser scanning path;
[0029] (2.2) A layer of Ni-Ti mixed powder with a thickness of 20μm is preset on the surface of the titanium substrate. The laser uses the parameters of 160W laser power, 15m/min scanning speed and 40μm scanning distance according to the generated laser scanning path. Scanning, the Ni and Ti in the mixed powder are melted in situ to generate NiTi shape memory alloy, forming a flat NiTi shape memory alloy melting layer on the titanium substrate;
[0030] (2.3) When a layer of NiTi shape memory alloy is formed, lower the titanium substrate by 20μm, and then preset a layer of Ni-Ti mixed powder with a thickness of 20μm on the molten layer; use the above laser processing parameters to follow the set path Scan and shape the newly preset Ni-Ti mixed powder layer to form a new molten layer;
[0031] (2.4) Repeat the above step (2.3) until the in-situ synthesis of the entire NiTi shape memory alloy is completed, and the entire laser melting and forming process is completed in a protective environment with water and oxygen content less than 10PPM. The formed part is cut from the titanium substrate to obtain a NiTi alloy part that is consistent with the design shape and has a shape memory function.

Example Embodiment

[0032] Example 2:
[0033] A method for directly preparing NiTi shape memory alloys of arbitrary shapes from element powders, including the following steps:
[0034] (1) Powder preparation: use pure Ni powder and pure Ti powder with a particle size of less than 50μm and the same average particle size as raw materials, and mix uniformly according to the Ni/Ti atomic ratio of 50.5:49.5;
[0035] (2) Use selective laser melting rapid prototyping method to prepare NiTi shape memory alloy of arbitrary shape:
[0036] (2.1) The mixed powder with the atomic ratio of Ni/Ti of 50.5:49.5 is used as the raw material, continuous YAG or fiber laser is used as the energy source, the focal spot diameter is 25μm, and the titanium plate is used as the forming substrate to transform any three-dimensional The graphic STL file is input to the SLM rapid prototyping equipment, which is layered and discretized by the slicing software to generate the laser scanning path;
[0037] (2.2) A layer of Ni-Ti mixed powder layer with a thickness of 10μm is preset on the surface of the titanium substrate. The laser uses the parameters of 160W laser power, 30m/min scanning speed and 25μm scanning distance according to the generated laser scanning path. Scanning, the Ni and Ti in the mixed powder are melted in situ to generate NiTi shape memory alloy, forming a flat NiTi shape memory alloy melting layer on the titanium substrate;
[0038] (2.3) When a layer of NiTi shape memory alloy layer is formed, lower the titanium substrate by 10μm, and then preset a layer of Ni-Ti mixed powder with a thickness of 10μm on the molten layer; use the above laser processing parameters to follow the set path Scan and shape the newly preset Ni-Ti mixed powder layer to form a new molten layer;
[0039] (2.4) Repeat the above step (2.3) until the in-situ synthesis of the entire NiTi shape memory alloy is completed, and the entire laser melting and forming process is completed in a protective environment with water and oxygen content less than 10PPM. The formed part is cut from the titanium substrate to obtain a NiTi alloy part that is consistent with the design shape and has a shape memory function.

Example Embodiment

[0040] Example 3:
[0041] A method for directly preparing NiTi shape memory alloys of arbitrary shapes from element powders, including the following steps:
[0042] (1) Powder preparation: use pure Ni powder and pure Ti powder with a particle size of less than 50μm and the same average particle size as raw materials, and mix uniformly according to the Ni/Ti atomic ratio of 50:50;
[0043] (2) Use selective laser melting rapid prototyping method to prepare NiTi shape memory alloy of arbitrary shape:
[0044] (2.1) The mixed powder with the atomic ratio of Ni/Ti of 50:50 is used as the raw material, continuous YAG or fiber laser is used as the energy source, the focal spot diameter is 30μm, and the titanium plate is used as the forming substrate. The graphic STL file is input to the SLM rapid prototyping equipment, which is layered and discretized by the slicing software to generate the laser scanning path;
[0045] (2.2) A layer of Ni-Ti mixed powder with a thickness of 20μm is preset on the surface of the titanium substrate. According to the generated laser scanning path, the laser uses the parameters of 170W laser power, 20m/min scanning speed, and 30μm scanning distance. Scanning, the Ni and Ti in the mixed powder are melted in situ to generate NiTi shape memory alloy, forming a flat NiTi shape memory alloy melting layer on the titanium substrate;
[0046] (2.3) When a layer of NiTi shape memory alloy is formed, lower the titanium substrate by 20μm, and then preset a layer of Ni-Ti mixed powder with a thickness of 20μm on the molten layer; use the above laser processing parameters to follow the set path Scan and shape the newly preset Ni-Ti mixed powder layer to form a new molten layer;
[0047] (2.4) Repeat the above step (2.3) until the in-situ synthesis of the entire NiTi shape memory alloy is completed, and the entire laser melting and forming process is completed in a protective environment with water and oxygen content less than 10PPM. The formed part is cut from the titanium substrate to obtain a NiTi alloy part that is consistent with the design shape and has a shape memory function.
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PUM

PropertyMeasurementUnit
Thickness20.0µm
Thickness10.0µm
Thickness15.0µm
tensileMPa
Particle sizePa
strength10

Description & Claims & Application Information

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