CN113600834B - Preparation method of high-niobium titanium-aluminum alloy with excellent room-temperature plasticity based on laser melting deposition - Google Patents

Abstract

The invention discloses a preparation method of a high-niobium titanium-aluminum alloy with excellent room-temperature plasticity based on laser melting deposition, which belongs to the technical field of high-temperature alloys and is characterized in that boron powder is used as reinforcing particles, and the addition amount of the boron powder is 0.05-0.13 wt%. The boron grain refiner is added to optimize the components of the high-niobium titanium-aluminum alloy, refine alloy grains and improve the room-temperature plasticity of the alloy; meanwhile, the temperature gradient between the substrate and the deposition layer is reduced through preheating, and cracks generated in the preparation of the high-niobium titanium-aluminum alloy based on laser melting deposition are eliminated and inhibited.

Description

A kind of preparation method of high niobium titanium aluminum alloy with excellent room temperature plasticity based on laser melting deposition

technical field

The invention relates to the technical field of high-temperature alloys, in particular to a preparation method of high-niobium-titanium-aluminum alloy with excellent room temperature plasticity based on laser melting deposition.

Background technique

Lightweight titanium-aluminum alloys with excellent high-temperature properties are considered to be important high-temperature structural materials in the future aviation field. However, the inherent brittleness of intermetallic compounds leads to low room temperature ductility of titanium-aluminum alloys, and cracks easily occur during processing, which seriously hinders its application development. In high-niobium-titanium aluminum alloys, the addition of a large amount of niobium element not only increases the high-temperature strength of the alloy, but also aggravates the room temperature brittleness of the alloy. In addition, the existence of ordered B2 phase not only further reduces the plasticity of the alloy, but also further aggravates the cracking problem of the alloy. The problems of poor plasticity and easy cracking of high-niobium-titanium aluminum alloys seriously affect their application in larger-scale industrialization.

In recent years, in order to improve the room temperature plasticity of titanium-aluminum-based alloys, researchers at home and abroad have carried out a lot of research work. At present, grain refinement is considered to be the only effective means to simultaneously improve the strength and plasticity of titanium-aluminum alloys. Studies have shown that: when the grain size of the alloy is 50nm, its room temperature plasticity reaches 50%, which is far more than the plasticity of conventional grain size, and it has superplasticity at room temperature; in the casting of titanium-aluminum alloy, the coarse casting is refined. The as-cast microstructure can significantly improve the mechanical properties of the as-cast high-niobium-titanium-aluminum alloy. Therefore, it is of great significance to obtain fine and uniform lamellar structure by refining grains and to improve the room temperature plasticity of high niobium-titanium aluminum alloys.

In addition, in the process of additive manufacturing, the powder material used for printing is a key factor affecting the quality of the printed product, which determines the forming capability boundary of the additive manufacturing technology. Due to the special surface structure of nanoparticles, there is nano-action energy between nanoparticles, which leads to the agglomeration of nanoparticles with each other. The long-term mixing of powders by high-energy ball milling greatly reduces the sphericity of alloy powder particles, resulting in a significant decrease in powder fluidity, which seriously affects the forming quality of additive manufacturing. In addition, high-energy ball milling is difficult to solve the problem that nano-reinforced particles are easy to agglomerate with each other. , resulting in agglomeration and segregation of nano-reinforced particles in additively manufactured shaped parts. Therefore, how to maintain the sphericity of alloy powder particles is also an important problem to be solved urgently in this field.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of high niobium titanium aluminum alloy with excellent room temperature plasticity based on laser melting deposition, so as to solve the technical problems existing in the above-mentioned prior art.

For achieving the above object, the present invention provides the following scheme:

A method for preparing a high-niobium-titanium-aluminum alloy with excellent room temperature plasticity based on laser melting deposition, which uses boron powder as reinforcing particles, and the addition amount of the boron powder is 0.05wt% to 0.13wt%.

Further, the above-mentioned preparation method of the high-niobium-titanium-aluminum alloy with excellent room temperature plasticity based on laser melting deposition includes the following steps:

(1) adding boron powder into an organic solvent to form a dispersion, and then dispersing by ultrasonic crushing to form a particle suspension;

(2) adding spherical high-niobium-titanium-aluminum alloy powder to the particle suspension obtained in step (1) and mixing uniformly to obtain a uniformly mixed suspension;

(3) mechanically stirring the uniformly mixed suspension obtained in step (2) for 1-2 hours, and then drying and sieving to obtain particle-enhanced high niobium-titanium-aluminum alloy powder;

(4) Preheating the substrate of the device for realizing laser melting deposition, and then using the laser melting deposition technology to process the particle-enhanced high-niobium-titanium-aluminum alloy powder obtained in step (3) to obtain the laser-based Fusion deposited high niobium titanium aluminum alloy with excellent room temperature plasticity.

Further, in step (2), the oxygen content of the spherical high-niobium-titanium-aluminum alloy powder is below 700 ppm, and the particle size is 53-150 μm. If the oxygen content in the spherical high-niobium-titanium-aluminum alloy powder is too high, it will affect the forming, and eventually lead to a large number of defects such as pores in the formed parts, and the high oxygen content will also seriously reduce the plasticity of the alloy.

Further, in step (1), the powder particle size of the boron powder is 90-120 nm.

Further, in step (1), the organic solvent is absolute ethanol, and the addition amount of the organic solvent is 10% to 20% of the weight of the spherical high niobium titanium aluminum alloy powder.

Further, in step (1), the frequency of the ultrasonic crushing and dispersion is 20-25KHz, and the time is 15-60min.

Further, in step (2), the method of uniform mixing is ultrasonic combined with mechanical stirring and dispersion, wherein the ultrasonic frequency is 20-25KHz, the stirring speed is 50-100r/min, and the time is 15-45min.

Further, it is characterized in that, in step (3), the drying process is performed in a vacuum drying oven, the drying temperature is 60-80° C., and the drying time is 12-24 h.

Further, in step (4), the preheating heating device adopts an electromagnetic induction coil, the electromagnetic induction coil is arranged on the support plate of the substrate, and the preheating temperature is 900-1000°C.

Further, in step (4), the processing and forming specifically includes: according to the processing path of the layered slicing information of the preset forming part CAD model, the powder synchronously sent by the nozzle is melted layer by layer, rapidly solidified, and layer by layer. Deposition, resulting in a prefabricated part.

In the present invention, elemental boron is used as the grain refiner, which can precipitate fine borides to pin the grain boundaries, inhibit the growth of crystal grains, and play the role of fine-grain strengthening; the precipitated borides hinder the movement of dislocations and play the role of precipitation strengthening; At the same time, the addition of boron can also improve the segregation of β phase and Al elements, and transform the columnar crystals into equiaxed crystals. In addition, the refined grains can also inhibit the rapid expansion of cracks and improve the comprehensive mechanical properties of the alloy.

The laser melting deposition technology of the present invention adopts the coaxial powder feeding method, the scanning speed is low, and the cooling speed is low, which helps to suppress the residual stress and the generation of the brittle _α2 phase when the titanium aluminum alloy is solidified. Moreover, during the laser melting deposition process, the height of the laser focusing point can be adjusted freely, the laser beam can be defocused above the deposition layer, and the powder can be fully preheated before entering the molten pool under a sufficiently high laser power to achieve the purpose of eliminating cracks. .

The uniform mixing method of the boron powder and the spherical high-niobium-titanium-aluminum alloy powder of the present invention is ultrasonic combined with mechanical stirring and dispersion. Ultrasound relies on the ultrasonic cavitation of the liquid and has a good dispersion effect in the liquid. When the ultrasonic vibration is transmitted into the liquid, it will stimulate a strong cavitation effect in the liquid, thus producing a large number of cavitation bubbles in the liquid. At the same time, due to the vibration and dispersion of ultrasonic waves, the solid and liquid are more fully mixed.

The present invention discloses the following technical effects:

(1) The present invention introduces elemental boron as a grain refiner, which plays a role of grain refinement strengthening. When the addition amount of boron is 0.13wt% of the alloy weight, the refining effect is the most significant; the precipitated boride hinders the dislocation movement. At the same time, it also effectively improves the segregation of β phase and Al elements, and transforms columnar crystals into equiaxed crystals. In addition, the refined grains can inhibit the rapid propagation of cracks and improve the comprehensive mechanical properties of the alloy.

(2) The present invention adopts the ultrasonic-stirring method to prepare the particle-enhanced high-niobium-titanium-aluminum alloy powder. This method has a wide range of raw materials, the preparation method is simple and easy to operate, and the preparation cost is low. On the basis of damage, the boron powder is well dispersed and uniformly dispersed and adsorbed on the spherical powder of high niobium titanium aluminum alloy by ultrasonic action. The particle-enhanced high-niobium-titanium-aluminum alloy powder prepared by the method has high sphericity and good fluidity, and meets the requirements of laser melting deposition technology.

(3) The present invention adopts laser melting deposition technology to prepare high-niobium-titanium-aluminum alloy, and selects the alloy with the same composition as the deposition layer as the substrate to reduce the thermal expansion coefficient between the substrate and the deposition layer; electromagnetic induction heating is used to pre-heat before deposition. For the thermal substrate, the temperature control device is used to make the substrate temperature not lower than 900°C during the deposition process. After the deposition, the temperature control device and the cooling device are used to control the cooling rate to reduce the temperature gradient between the substrate and the deposition layer.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the SEM image of the alloy powder, wherein a is the SEM image of the high-niobium-titanium-aluminum alloy powder raw material used in all the examples, and b is the SEM image of the particle-enhanced high-niobium-titanium-aluminum alloy powder prepared in step (3) of Example 3 picture.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail, which detailed description should not be construed as a limitation of the invention, but rather as a more detailed description of certain aspects, features, and embodiments of the invention.

It should be understood that the terms described in the present invention are only used to describe particular embodiments, and are not used to limit the present invention. Additionally, for numerical ranges in the present disclosure, it should be understood that each intervening value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated value or intervening value in that stated range is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention relates. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials in connection with which the documents are referred. In the event of conflict with any incorporated document, the content of this specification controls.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the present invention. The description and examples of the present invention are exemplary only.

As used herein, "comprising," "including," "having," "containing," and the like, are open-ended terms, meaning including but not limited to.

Example 1

Raw materials used in this example:

Spherical high niobium titanium aluminum alloy powder: dosage of 200g, particle size of 53-150μm, oxygen content below 700ppm, the proportion of niobium in the alloy powder is 17.41wt%, the proportion of titanium is 53.13wt%, and the proportion of aluminum is 29.46wt%; the SEM image of the raw material spherical high niobium titanium aluminum alloy powder is shown in Fig. 1(a).

Boron powder: dosage is 0.1g, particle size is 90-110nm;

Anhydrous ethanol: the dosage is 20g.

Specific steps are as follows:

(1) Add 0.1g of boron powder to 20g of absolute ethanol to form a dispersion, and under the condition of ultrasonic frequency of 20KHz, after ultrasonic crushing and dispersing for 15min, a reinforced particle suspension is formed.

(2) 200g of spherical high-niobium titanium-aluminum alloy powder was added to the reinforced particle suspension obtained in step (1), and stirred for 15 minutes by the method of ultrasonic combined with mechanical stirring and dispersion, and uniformly mixed to obtain a uniformly mixed suspension. Among them, the ultrasonic frequency of ultrasonic combined with mechanical stirring dispersion is 20KHz, and the stirring speed of mechanical stirring is 50r/min.

(3) Stir the uniformly mixed suspension obtained in step (2) for 2 hours under the condition that the stirring power is 60W and the stirring speed is 100r/min, until the organic solvent is basically volatilized, and then in a vacuum drying oven, under the condition of 60°C Drying time is 24h, sieving to obtain particle-enhanced high-niobium-titanium-aluminum alloy powder;

(4) Use an electromagnetic induction heating device to preheat the substrate to 900°C, and then keep the substrate temperature not lower than 900°C. According to the processing path of the pre-set CAD model of the molded part, the laser will synchronously send the powder to the nozzle. Layer-by-layer melting, rapid solidification, and layer-by-layer deposition finally obtain a preset forming part, that is, a high-niobium-titanium-aluminum alloy with excellent room temperature plasticity based on laser fusion deposition.

Example 2

Raw materials used in this example:

Spherical high niobium titanium aluminum alloy powder: dosage of 200g, particle size of 53-150μm, oxygen content below 700ppm, the proportion of niobium in the alloy powder is 17.41wt%, the proportion of titanium is 53.13wt%, and the proportion of aluminum is 29.46wt%; the SEM image of the raw material spherical high niobium titanium aluminum alloy powder is shown in Fig. 1(a).

Boron powder: dosage is 0.15g, particle size is 90-110nm;

Anhydrous ethanol: the dosage is 30g.

Specific steps are as follows:

(1) Add 0.15g of boron powder to 30g of absolute ethanol to form a dispersion, and under the condition of ultrasonic frequency of 23KHz, after ultrasonic crushing and dispersing for 30min, a reinforced particle suspension is formed.

(2) Adding spherical high-niobium-titanium-aluminum alloy powder to the reinforced particle suspension obtained in step (1), and stirring for 30 minutes by means of ultrasonic combined with mechanical stirring and dispersing, and uniformly mixing to obtain a uniformly mixed suspension. Among them, the ultrasonic frequency of ultrasonic combined with mechanical stirring dispersion is 23KHz, and the stirring speed of mechanical stirring is 80r/min.

(3) Stir the uniformly mixed suspension obtained in step (2) for 1.5 hours under the condition that the stirring power is 100W and the stirring speed is 200r/min, until the organic solvent is basically volatilized, and then in a vacuum drying box, 70 ℃ conditions The lower drying time is 20h, and the sieve treatment is carried out to obtain particle-enhanced high-niobium-titanium-aluminum alloy powder;

(4) Preheat the substrate to 950°C with the electromagnetic induction coil arranged on the pallet of the substrate, and then maintain the substrate temperature not lower than 900°C. The powder fed by the nozzle synchronously undergoes layer-by-layer melting, rapid solidification, and layer-by-layer deposition, and finally obtains a preset molded part, that is, a high-niobium-titanium-aluminum alloy with excellent room temperature plasticity based on laser melting deposition.

Example 3

Raw materials used in this example:

Spherical high niobium titanium aluminum alloy powder: dosage of 200g, particle size of 53-150μm, oxygen content below 700ppm, the proportion of niobium in the alloy powder is 17.41wt%, the proportion of titanium is 53.13wt%, and the proportion of aluminum is 29.46wt%;; the SEM image of the raw material spherical high niobium titanium aluminum alloy powder is shown in Fig. 1(a).

Boron powder: dosage is 0.26g, particle size is 100-120nm;

Anhydrous ethanol: the dosage is 40g.

Specific steps are as follows:

(1) Add 0.26g of boron powder to 40g of absolute ethanol to form a dispersion, and under the condition of ultrasonic frequency of 25KHz, after ultrasonic crushing and dispersing for 60min, a reinforced particle suspension is formed.

(2) Adding spherical high-niobium-titanium-aluminum alloy powder to the reinforced particle suspension obtained in step (1), and stirring for 45 minutes by ultrasonic combined with mechanical stirring and dispersing, and uniformly mixing to obtain a uniformly mixed suspension. Among them, the ultrasonic frequency of ultrasonic combined with mechanical stirring dispersion is 25KHz, and the stirring speed of mechanical stirring is 100r/min.

(3) Stir the uniformly mixed suspension obtained in step (2) for 1 hour under the condition that the stirring power is 120W and the stirring speed is 300r/min, until the organic solvent is basically volatilized, and then in a vacuum drying box, under the condition of 80°C The drying time is 12h, and the sieve treatment is carried out to obtain particle-enhanced high-niobium-titanium-aluminum alloy powder;

(4) Use an electromagnetic induction heating device to preheat the substrate to 1000°C, and then keep the substrate temperature not lower than 900°C. According to the processing path of the pre-set CAD model of the molded part, the laser synchronously sends the powder to the nozzle. Layer-by-layer melting, rapid solidification, and layer-by-layer deposition finally obtain a preset forming part, that is, a high-niobium-titanium-aluminum alloy with excellent room temperature plasticity based on laser fusion deposition.

The SEM image of the high-niobium-titanium aluminum alloy prepared in this example is shown in Figure 1(b). adsorption on high-niobium-titanium-aluminum alloy spherical powder. It is illustrated that the particle-enhanced high-niobium-titanium-aluminum alloy powder prepared by the method in this example has high sphericity and good fluidity.

Comparative Example 1

Same as Example 1, the only difference is that no boron element is added.

Comparative Example 2

Same as Comparative Example 1, the difference is only that the preparation method is vacuum smelting.

Comparative Example 3

Same as Embodiment 3, the difference is only that the substrate is not preheated.

The formability, inter-lamellar spacing, tensile strength and elongation data of the high niobium-titanium aluminum alloys prepared in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1 below, in which the detection of grain size The standard is E 112-96, and the testing standard for tensile strength and elongation is GBT 228-2002.

Table 1

Example Formability Interlayer spacing, μm Tensile strength, MPa Elongation, % Example 1 not cracked 0.37～0.49 556 0.34 Example 2 not cracked 0.24～0.35 619 0.39 Example 3 not cracked 0.11～0.22 749 0.50 Comparative Example 1 not cracked 0.52～1.11 445 0.25 Comparative Example 2 not cracked 30～40 273 0.14 Comparative Example 3 macro cracking - - -

It can be seen from Table 1 that:

(1) Preheating the substrate by electromagnetic induction heating reduces the temperature gradient between the substrate and the deposition layer, which can well suppress the formation of cracks during the laser melting deposition process, and prepare crack-free, high-density and microstructure High-niobium-titanium-aluminum alloy samples with uniform composition;

(2) Compared with the vacuum melting forming technology, the high-niobium-titanium aluminum alloy formed by the laser melting deposition technology has a finer structure, and the tensile strength and room temperature plasticity of the alloy are higher; The grain refinement improves the room temperature plasticity and tensile strength of the alloy; when the addition of boron element reaches 0.13wt%, the alloy exhibits the best comprehensive mechanical properties.

The above-mentioned embodiments are only to describe the preferred mode of the present invention, but not to limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art can Variations and improvements should fall within the protection scope determined by the claims of the present invention.

Claims (9)

1. A preparation method of a high-niobium-titanium-aluminum alloy with excellent room temperature plasticity based on laser melting deposition, characterized in that it uses boron powder as reinforcing particles, and the addition of the boron powder is 0.05 to 0.13wt%; The preparation method comprises the following steps: (1) Adding boron powder into an organic solvent to form a dispersion liquid, which is subjected to ultrasonic crushing and dispersion treatment to form a particle suspension; (2) adding spherical high-niobium-titanium-aluminum alloy powder to the particle suspension obtained in step (1) and mixing uniformly to obtain a uniformly mixed suspension; the proportion of niobium in the spherical high-niobium-titanium-aluminum alloy powder is 17.41 wt%; (3) mechanically stirring the uniformly mixed suspension obtained in step (2) for 1-2 hours, and then drying and sieving to obtain particle-enhanced high-niobium-titanium-aluminum alloy powder; (4) Preheating the substrate of the device for realizing laser melting deposition to 900-1000° C., and then using the laser melting deposition technology to process the particle-enhanced high-niobium-titanium-aluminum alloy powder obtained in step (3) to obtain The high niobium titanium aluminum alloy with excellent room temperature plasticity based on laser melting deposition. 2 . The method for preparing high niobium titanium aluminum alloy with excellent room temperature plasticity based on laser melting deposition according to claim 1 , wherein in step (2), the oxygen content of the spherical high niobium titanium aluminum alloy powder is At 700 ppm or less, the particle size is 53 to 150 μm. 3 . The preparation method of high niobium titanium aluminum alloy with excellent room temperature plasticity based on laser melting deposition according to claim 1 , wherein in step (1), the powder particle size of the boron powder is 90-120 nm. 4 . . 4 . The preparation method of high niobium titanium aluminum alloy with excellent room temperature plasticity based on laser melting deposition according to claim 1 , wherein in step (1), the organic solvent is anhydrous ethanol, and the organic solvent is anhydrous ethanol. 5 . The added amount of the solvent is 10% to 20% of the weight of the spherical high niobium titanium aluminum alloy powder. 5 . The method for preparing a high niobium-titanium-aluminum alloy with excellent room temperature plasticity based on laser melting deposition according to claim 1 , wherein in step (1), the frequency of the ultrasonic fragmentation and dispersion is 20 to 25 KHz, 6 . The time is 15 to 60 minutes. 6 . The preparation method of high niobium titanium aluminum alloy with excellent room temperature plasticity based on laser melting deposition according to claim 1 , wherein in step (2), the uniform mixing method is ultrasonic combined with mechanical stirring For dispersion, the ultrasonic frequency is 20-25KHz, the stirring speed is 50-100r/min, and the time is 15-45min. 7 . The preparation method of high niobium titanium aluminum alloy with excellent room temperature plasticity based on laser melting deposition according to claim 1 , wherein in step (3), the drying process is carried out in a vacuum drying oven, and the drying process is carried out in a vacuum drying oven. 8 . The temperature is 60～80℃, and the drying time is 12～24h. 8. The preparation method of high niobium titanium aluminum alloy with excellent room temperature plasticity based on laser melting deposition according to claim 1, in step (4), the preheating heating device adopts an electromagnetic induction coil, the electromagnetic induction The coils are arranged on the pallet of the base plate. 9 . The preparation method of high niobium titanium aluminum alloy with excellent room temperature plasticity based on laser melting deposition according to claim 1 , wherein in step (4), the processing and forming specifically comprises: forming parts according to presets. 10 . The processing path of the layered slice information of the CAD model, the laser synchronously sends the powder from the nozzle to melt layer by layer, rapidly solidify, and deposit layer by layer, and finally obtain the preset molding part.

Images