A method for laser 4D printing of titanium nickel hafnium shape memory alloy parts

Abstract

The present application relates to the field of additive manufacturing titanium alloy material processing and preparation, and particularly relates to a method for laser 4D printing of titanium nickel hafnium shape memory alloy parts. The method for forming titanium nickel hafnium shape memory alloy parts comprises designing a 4D printing model according to the actual use environment of the parts, and simultaneously selecting titanium nickel hafnium pre-alloy powder with different component proportions; the titanium nickel hafnium shape memory alloy parts are prepared by using the pre-alloy powder through laser 4D printing; the whole part is annealed and then cut to obtain the parts, and the parts are post-processed to obtain intelligent components. The integrated self-controllable medium-temperature intelligent components with good comprehensive mechanical properties can be obtained by using the present application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of additive manufacturing of titanium alloy material processing and preparation, in particular to a method for laser 4D printing of titanium nickel hafnium shape memory alloy parts. BACKGROUND

[0002] Shape memory alloy (SMA) is an intermetallic compound with solid-state phase transition, which has good biocompatibility, corrosion resistance, high damping and excellent comprehensive mechanical properties. As a functional material, the shape memory effect or superelasticity of shape memory alloy is widely used in industrial, biomedical, building structure, precision instrument and other fields, and is paid more and more attention by researchers. Although shape memory alloy has excellent mechanical properties, it is easy to cause adhesion, burr and other problems in the processing process, which causes great damage to the tool, limits the expansion of its application range, and the laser 4D printing technology can directly form a metal part with good metallurgical bonding, close to complete densification and excellent performance by point-by-point scanning melting, row-by-row scanning and layer-by-layer scanning.

[0003] Titanium nickel hafnium shape memory alloy is developed on the basis of titanium nickel shape memory alloy, and the problem of insufficient phase transition temperature of titanium nickel alloy less than 100 DEG C is solved by adding alloying elements, so that it can be used in industrial high temperature environment. At present, there is no related report and introduction of 4D printing of titanium nickel hafnium shape memory alloy parts at home and abroad, and the parameters of laser 4D printing will affect the performance of the formed alloy, so it is necessary to limit the process accordingly. SUMMARY

[0004] In order to solve the problems existing in the conventional processing of titanium nickel hafnium shape memory alloy, the purpose of the present application is to provide a method for laser 4D printing of titanium nickel hafnium shape memory alloy parts, which uses laser printing forming technology to form intelligent components at medium temperature.

[0005] In order to achieve the above purpose, the technical scheme of the present application is:

[0006] A method for laser 4D printing of titanium nickel hafnium shape memory alloy parts, the specific process is:

[0007] (1) The method for forming titanium nickel hafnium shape memory alloy parts comprises designing a 4D printing model according to the actual use environment of the parts, and selecting titanium nickel hafnium pre-alloy powder with different component proportions;

[0008] (2) The titanium nickel hafnium shape memory alloy parts are prepared by using the pre-alloy powder by laser 4D printing;

[0009] The laser power is 50W-150W, the scanning speed is 400mm / s-1000mm / s, the powder layer thickness is 25um-50um, the scanning interval is 700um-1200um, the substrate heating temperature is 100 DEG C-300 DEG C, and the printing substrate material is titanium-nickel-based shape memory alloy;

[0010] (3) cutting the integral component after annealing to obtain the sub-components, and performing post-treatment on the sub-components to obtain the intelligent component; the integral component of the 4D printing technology is annealed at 800 DEG C-900 DEG C for 0.5h-2h, and then the component is removed from the substrate.

[0011] The laser 4D printing titanium-nickel-hafnium shape memory alloy sub-component method uses titanium-nickel-hafnium pre-alloy powder with adjustable composition, and the powder is prepared by a crucible-free gas atomization method, and the particle size range is ≤40um.

[0012] The laser 4D printing titanium-nickel-hafnium shape memory alloy sub-component method is a complex structure and shape of solid, porous and solid and porous flow channel combination.

[0013] The laser 4D printing titanium-nickel-hafnium shape memory alloy sub-component method is a complex structure and shape of solid, porous and solid and porous flow channel combination.

[0014] The design idea of the application is:

[0015] The application proposes a method for preparing titanium-nickel-hafnium shape memory alloy sub-components by using laser 4D printing technology, directly preparing components with required shapes and structures by laser printing, and achieving intelligent target of the prepared components through appropriate treatment.

[0016] The application has the advantages and beneficial effects that:

[0017] The application designs corresponding structure and shape components according to environmental requirements, changes alloy composition to adapt to different use environments, uses and adjusts laser 4D printing selective melting parameters to obtain complex sub-components, avoids complex conventional mechanical processing process and difficulty, and finally obtains medium-temperature intelligent titanium-nickel-hafnium shape memory alloy sub-components through appropriate post-treatment. DETAILED DESCRIPTION OF DRAWINGS:

[0018] Figures 1(a)-1(c) Ti 29.8 Ni 50.2 Hf 20850 Heat treatment cross section (a) and longitudinal section (b) original metallographic microstructure and (c) phase transition curve. In Fig. 1 (c), the abscissa Temperature (℃) represents temperature, and the ordinate Heatfolw (mW / mg) represents heat flow.

[0019] Figures 2(a)-2(c) 3D printed Ti 29.6 Ni 50.4 Hf 20 850 Heat treatment cross section (a) and longitudinal section (b) original metallographic microstructure and (c) phase transition curve. In Fig. 2 (c), the abscissa Temperature (℃) represents temperature, and the ordinate Heatfolw (mW / mg) represents heat flow.

[0020] Figures 3(a)-3(c) 3D printed Ti 29.4 Ni 50.6 Hf 20 850 Heat treatment cross section (a) and longitudinal section (b) original metallographic microstructure and (c) phase transition curve. In Fig. 3 (c), the abscissa Temperature (℃) represents temperature, and the ordinate Heatfolw (mW / mg) represents heat flow. DETAILED DESCRIPTION

[0021] In the implementation process, the 4D printed titanium nickel hafnium shape memory alloy parts of the application are prepared by dosing according to the required alloy composition to prepare electrodes, and then pre-alloyed powder is prepared by a crucible-free induction melting gas atomization method. According to the actual use environment requirements, a certain structure and shape of the part is prepared by using laser 4D printing technology, and the intelligent performance is adjusted by combining a certain heat treatment system. The 4D printed component is heat treated at 400℃-600℃ for 2h-10h with or without constraint to regulate the performance. The constrained heat treatment refers to the heat treatment of the deformed open and close valve after being fixed in a special clamp. The unconstrained heat treatment refers to direct heat treatment without using additional clamps.

[0022] In the following, the application is further described in detail through comparative examples and examples.

[0023] Example 1

[0024] In this embodiment, the method for laser 4D printing titanium nickel hafnium shape memory alloy parts is as follows:

[0025] The chemical composition of the titanium nickel hafnium shape memory alloy is that the atomic ratio of Ti 29.8 Ni 50.2 Hf 20, the pre-alloyed powder is prepared by a rod preparation method of crucible-free induction melting gas atomization, the particle size of the pre-alloyed powder is ≤40 μm, and the pre-alloyed powder is prepared into a titanium-nickel-hafnium shape memory alloy part by using a laser 4D printing method. The specific parameters of the laser 4D printing are as follows: a power of 95 W, a scanning speed of 780 mm / s, a scanning interval of 90 μm, a powder laying thickness of 30 μm, and substrate heating of 150 ℃. After the overall shaped part and the substrate are annealed at 850 ℃ for 1 h, the final part is cut, at which time the phase transition curve of the intelligent part is shown in FIG. 1, and it can be seen that there is obvious phase transition behavior, and it has intelligent use prospects. In order to further adjust the intelligent performance, the alloy can be subjected to constrained aging treatment at 550 ℃ for 3 h.

[0026] Embodiment 2

[0027] In this embodiment, the method for laser 4D printing a titanium-nickel-hafnium shape memory alloy part is as follows:

[0028] The chemical composition of the titanium-nickel-hafnium shape memory alloy is as follows: the atomic ratio of Ti 29.6 Ni 50.4 Hf 20 , the pre-alloyed powder is prepared by a rod preparation method of crucible-free induction melting gas atomization, the particle size of the pre-alloyed powder is ≤30 μm, and the pre-alloyed powder is prepared into a titanium-nickel-hafnium shape memory alloy part by using a laser 4D printing method. The specific parameters of the laser 4D printing are as follows: a power of 120 W, a scanning speed of 950 mm / s, a scanning interval of 90 μm, a powder laying thickness of 30 μm, and substrate heating of 200 ℃. After the overall shaped part and the substrate are annealed at 800 ℃ for 2 h, the final part is cut, at which time the phase transition curve of the intelligent part is shown in FIG. 2, and it can be seen that there is obvious phase transition behavior, and it has intelligent use prospects. In order to further adjust the intelligent performance, the alloy can be subjected to constrained aging treatment at 500 ℃ for 5 h.

[0029] Embodiment 3

[0030] In this embodiment, the method for laser 4D printing a titanium-nickel-hafnium shape memory alloy part is as follows:

[0031] The chemical composition of the titanium-nickel-hafnium shape memory alloy is as follows: the atomic ratio of Ti 29.4 Ni 50.6 Hf 20The pre-alloyed powder is prepared by a rod preparation crucible-free induction melting gas atomization method, the particle size of the pre-alloyed powder is ≤20 μm, and the pre-alloyed powder is prepared into a titanium-nickel-hafnium shape memory alloy part by a laser 4D printing method. The specific parameters of the laser 4D printing are as follows: power 140 W, scanning speed 1200 mm / s, scanning interval 90 μm, powder laying thickness 30 μm, and substrate heating 300 ℃. The whole shaped part and the substrate are annealed at 900 ℃ for 0.5 h, and then the final part is cut, and the phase transition curve of the intelligent part is shown in FIG. 3. It can be seen that there is obvious phase transition behavior, and the intelligent part has a good intelligent use prospect. In order to further adjust the intelligent performance, the alloy can be subjected to unconstrained aging treatment at 450 ℃ for 8 h.

[0032] The results of the embodiments show that the self-controllable medium-temperature intelligent component can be obtained by the application, and the self-controllable medium-temperature intelligent component has good comprehensive mechanical properties.

[0033] The above is only the best case of the application, and does not limit the application. Any simple modification, change and equivalent change of the above embodiments according to the technical essence of the application still belong to the protection scope of the technical scheme of the application.

Claims

1. A method for laser 4D printing titanium-nickel-hafnium shape memory alloy parts, characterized in that, The specific process is as follows: (1) The method for forming titanium-nickel-hafnium shape memory alloy parts includes designing a 4D printing model according to the actual use environment of the parts, and selecting titanium-nickel-hafnium pre-alloy powders with different composition ratios; the composition of the titanium-nickel-hafnium pre-alloy powders used is adjustable, the powders are prepared by crucibleless gas atomization method, and the particle size range is ≤40μm; (2) Titanium-nickel-hafnium shape memory alloy parts were prepared by using pre-alloyed powder through laser 4D printing; During laser 4D printing, the laser power is 95 W ~ 120 W, the scanning speed is 400 mm / s ~ 950 mm / s, the powder layer thickness is 30 μm, the scanning spacing is 90 μm, the substrate heating temperature is 150℃ ~ 300℃, and the substrate material used is a titanium-nickel-based shape memory alloy. The atomic ratio of this titanium-nickel-hafnium shape memory alloy is Ti. 29.8 Ni 50.2 Hf 20 or Ti 29.6 Ni 50.4 Hf 20 ; (3) After annealing the whole component, cut it to obtain the parts, and perform post-processing on the parts to obtain the intelligent components; after annealing the whole component and substrate of 4D printing technology at 800℃~900℃ for 0.5h~2h, remove the component from the substrate; The properties of 4D printed components are controlled by heat treatment with or without constraint at 400℃~600℃ for 2h~10h.

2. The method for laser 4D printing titanium-nickel-hafnium shape memory alloy parts according to claim 1, characterized in that, 4D printed parts are complex structures and shapes that combine solid, porous, and solid and porous flow channels.

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