CN115522101A - Fe-containing double-phase titanium-based alloy and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of aerospace materials and biomedicine, in particular to a low-cost high-strength biphase titanium-based alloy containing Fe and a preparation method thereof. The titanium-based alloy is prepared by smelting sponge titanium, industrial pure aluminum, pure tin and industrial pure iron, and comprises the following components in percentage by mass: al:1% -5%, sn:2.5% -6%, fe:2 to 8 percent of Ti element and other inevitable impurities as the rest. Compared with the titanium-based alloy (Ti-5 Al-2.5 Sn) without the Fe element, the alloy prepared by adding the Fe element has the advantages that the organizational structure is improved, the mechanical property is improved, the yield strength is improved by 10.04-55.02 percent, and the tensile strength is improved by 11.88-50.78 percent. The novel biphase titanium-based alloy provided by the invention has the advantages of low raw material cost, simple preparation method, excellent mechanical property and environmental friendliness, and has a wider industrial application range compared with the traditional titanium alloy.

Description

A kind of Fe-containing dual-phase titanium-based alloy and preparation method thereof

technical field

The invention relates to the technical fields of aerospace materials and biomedicine, in particular to an Fe-containing dual-phase titanium-based alloy and a preparation method thereof.

Background technique

Titanium (Ti) plays an irreplaceable role in my country's high-end manufacturing industries such as aerospace, marine ships, and biomedicine. Titanium alloys prepared from other metals and titanium have excellent properties such as high strength, low density, and high and low temperature resistance. . Among them, Ti-6Al-4V is a typical dual-phase titanium-based alloy, which has high specific strength and good corrosion resistance, and its long-term working temperature can reach 400 ° C. It is one of the most widely used titanium alloys at present. . However, due to the high price of the β-stabilizing element vanadium (V) contained in this alloy, the industrial production of Ti-6Al-4V alloy is limited, and it is limited to high-precision industries. However, in the prior art for preparing vanadium-free dual-phase titanium-based alloys, chromium (Cr) elements, which are more polluting to the environment, are often contained. Therefore, how to prepare titanium-based alloy materials with the advantages of low cost, high strength, and environmental protection has become one of the key directions of current research, development and application.

Contents of the invention

In view of the above technical problems, the present invention provides a low-cost high-strength dual-phase titanium-based alloy containing Fe and a preparation method thereof. The alloy does not need to add vanadium and chromium elements, and has the advantages of low cost, high strength, and low pollution.

In order to achieve the above-mentioned purpose of the invention, the embodiment of the present invention adopts the following technical solutions:

An Fe-containing dual-phase titanium-based alloy, including the following components in the following mass percentages: Al: 1%-5%, Sn: 2.5%-6%, Fe: 2%-8%, and the balance is Ti and others Avoid impurities.

Iron (Fe), as a commonly used element, has the advantages of wide geographical distribution, high crustal content and low production cost, and is a common alloy addition element. At the same time, iron is also a typical eutectoid β-stable element that lowers the phase transition temperature. It has a good strengthening effect and a strong ability to stabilize the β-phase. Its β-phase stabilization effect is better than that of Nb, Ta, Cr and Mo. No mesophase is produced during thermal processing and heat treatment. The iron element added according to the above mass percentage will not affect the mechanical properties of the titanium alloy, but can improve the tensile strength and yield strength of the titanium-based alloy.

Aluminum (Al) is the most abundant metal element in the earth's crust. The aluminum element added in the above mass percentage can increase the ductility of the dual-phase titanium-based alloy and improve the strength of the alloy. However, when the content of aluminum element added in the titanium-based alloy exceeds 6%, the intermetallic compound Ti ₃ Al which causes the embrittlement of the titanium alloy will be precipitated, thereby reducing the ductility of the titanium alloy.

Adding a specific amount of tin (Sn) element in the titanium-based alloy can play a role of solid solution strengthening and improve the mechanical properties and heat resistance of the titanium-based alloy at room temperature and high temperature. If the tin element is added too much, it will Reduce the plasticity of the obtained titanium alloy.

In combination with the first aspect, the raw material of the Al can be industrial pure aluminum with a purity of more than 99.9%;

The raw material of the Sn can be industrial pure tin with a purity of more than 99.9%;

The raw material of the Fe can be industrial pure iron with a carbon content below 0.04%;

The raw material of the Ti can be titanium sponge with a purity of more than 99.9%.

The sources of the above elements are all industrial raw materials, which are easy to obtain, low in cost and less in environmental pollution.

In the second aspect, the preparation method of the dual-phase titanium-based alloy comprises sequentially melting and heat-treating the raw materials of the components according to the mass percentages of the above-mentioned components to obtain the dual-phase titanium-based alloy.

The comprehensive mechanical properties of the obtained dual-phase titanium-based alloy can be effectively improved by smelting and microstructure-optimized heat treatment of the raw materials whose composition mass percentages are as described above, and can effectively prevent the workpiece of the obtained dual-phase titanium-based alloy from being damaged during service. resulting stress cracking.

In combination with the second aspect, the raw materials of each component are granular, and the preparation method further includes cleaning the granular raw materials with an organic solution, and cleaning the raw materials of Fe and Ti with an acid solution.

Cutting the raw materials of each component into granules can make the mixing of various elements more uniform during the smelting process; the purpose of cleaning the metal particles is to remove impurities, oil stains and oxide layer inclusions on the surface of the metal particles, so as to avoid introducing unnecessary impurities and affecting Properties of duplex titanium-based alloys.

With reference to the second aspect, the organic solution includes acetone and absolute ethanol, and the acid in the acid solution includes at least one of hydrofluoric acid, nitric acid and sulfuric acid.

Preferably, the volume ratio of hydrofluoric acid, nitric acid and water is 1-3:2-3:3-6, more preferably, the volume ratio of hydrofluoric acid, nitric acid and water is 2:2:5.

Preferably, the volume ratio of sulfuric acid and water is 1-3:7-9, more preferably, the volume ratio of sulfuric acid and water is 2:8.

With reference to the second aspect, the melting uses a non-consumable vacuum arc melting furnace, and the protective gas is an inert gas.

The smelting furnace has high power and short smelting time, which can effectively prevent the loss of metal elements caused by volatilization during the smelting process. During the smelting process, inert gas is used as a protective gas to avoid pollution caused by the reaction of metals with O, N and other elements in the air, so as to ensure that the smelting process is not disturbed.

In combination with the second aspect, the tissue optimization heat treatment uses a vacuum tube resistance furnace as the heat treatment furnace, and the protective gas is an inert gas, preferably argon.

With reference to the second aspect, the heating temperature of the tissue optimization heat treatment is 900°C to 1100°C.

The heating temperature should be kept in the temperature range corresponding to the α single-phase region of the titanium-based alloy. If the heating temperature is too low, it is not conducive to the precipitation of the α phase, and it is easy to cause stress concentration; if the heating temperature is too high, recrystallization will easily occur, making the α phase grains too coarse, which will affect the comprehensive mechanical properties of the dual-phase titanium-based alloy. .

With reference to the second aspect, the heat preservation time for the tissue optimization heat treatment is 10 minutes to 60 minutes.

If the holding time is too short, the precipitation of the α phase will be incomplete, and the stress concentration phenomenon cannot be eliminated; if the holding time is too long, recrystallization will easily occur in the α phase, resulting in excessively large grains, which will affect the comprehensive mechanical properties of the titanium-based alloy. .

The beneficial effect of the present invention is that: the Fe-containing dual-phase titanium-based alloy and the preparation method provided by the present invention realize the control of the production cost and mechanical properties of the new titanium-based alloy by changing the added elements in the titanium-based alloy. This method adopts iron (Fe) element with wide content distribution and low production cost as the addition element of titanium-based alloy, avoids the use of expensive vanadium (V) element and chromium (Cr) element that pollutes the environment, and is economical and environmentally friendly. . By introducing iron and optimizing the structure of the obtained alloy in the α-phase region, the comprehensive mechanical properties of the dual-phase titanium-based alloy are effectively improved. Compared with the titanium-based alloy Ti-5Al-2.5Sn without iron, the microstructure improved, the resulting alloy structure is a fine lath-like α phase, and with the addition of Fe elements, obvious β grain boundaries can be observed, which improves the mechanical properties, and the yield strength increases by 10.04% to 55.02%. Strength increased by 11.88% to 50.78%. The invention has convenient raw material acquisition, simple smelting process, and the obtained dual-phase titanium-based alloy has excellent mechanical properties and broad application prospects.

Description of drawings

Fig. 1 is the tensile sample cut out to the button ingot that structure optimization heat treatment obtains in embodiment 1～3 and comparative example 1, comparative example 2;

Fig. 2 is the X-ray diffraction result of embodiment 1～3 gained duplex titanium-based alloy;

Fig. 3 is the microstructure diagram of the obtained dual-phase titanium-based alloy of embodiment 1;

Fig. 4 is the microstructural figure of embodiment 2 gained dual-phase titanium base alloy;

5 is a microstructure diagram of the dual-phase titanium-based alloy obtained in Example 3.

detailed description

In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Example 1

This embodiment provides a dual-phase titanium-based alloy, the preparation method of which is:

(1) Pretreatment: get raw material sponge titanium (purity is 99.95wt%), industrial pure aluminum (purity is 99.99wt%), industrial pure tin (purity is 99.95wt%) and industrial pure iron (carbon content is 0.04wt%) % or less), cut it into several particles with a size of 1mm × 1mm × 1mm by wire cutting technology, place the raw material particles in a mixed solution with a volume ratio of acetone and absolute ethanol of 2:4 for 10 minutes to treat the surface cleaning. Subsequently, the titanium sponge particles were placed in an aqueous solution of hydrofluoric acid and nitric acid to pickle the surface, wherein the volume ratio of hydrofluoric acid, nitric acid and water was 1:2:3; industrial pure iron particles were placed in sulfuric acid The surface is pickled in an aqueous solution, where the volume ratio of sulfuric acid and water is 1:7. After pickling for 120s, place it in absolute ethanol for ultrasonic cleaning for 8 minutes, dry it with a hair dryer, and pack it into a bag for later use.

(2) Smelting: Mix the pretreated granular raw materials according to the proportion, among which, industrial pure aluminum accounts for 1wt%, industrial pure tin accounts for 6wt%, industrial pure iron accounts for 2wt%, and the rest is sponge titanium. The alloy raw material with a mass of 50g is put into the water-cooled copper crucible of GDJ500C non-consumable vacuum arc melting furnace, and the cooling water circulation system is adopted and vacuumized and filled with argon for protection. Each alloy ingot needs to be smelted 5 times repeatedly to obtain buttons ingot.

(3) Structure optimization heat treatment: conduct structure optimization heat treatment on the button ingot obtained by smelting, use argon as the protective atmosphere in a vacuum tube resistance furnace as the heat treatment furnace, heat to 1100 ° C, keep it for 10 minutes, and then cool with the furnace to obtain the final α +β-type duplex titanium-based alloy material.

Example 2

This embodiment provides a dual-phase titanium-based alloy, the preparation method of which is:

(1) Pretreatment: get raw material sponge titanium (purity is 99.95wt%), industrial pure aluminum (purity is 99.99wt%), industrial pure tin (purity is 99.95wt%) and industrial pure iron (carbon content is 0.04wt%) % or less), cut it into several particles with a size of 2mm × 2mm × 2mm by wire cutting technology, place the raw material particles in a mixed solution with a volume ratio of acetone and absolute ethanol of 4:6 and soak for 8 minutes on its surface cleaning. Subsequently, the titanium sponge particles are placed in an aqueous solution of hydrofluoric acid and nitric acid to pickle the surface, wherein the volume ratio of hydrofluoric acid, nitric acid and water is 2:2.5:4.5; industrial pure iron particles are placed in sulfuric acid The surface is pickled in an aqueous solution, in which the volume ratio of sulfuric acid and water is 2:8. After pickling for 100s, place it in absolute ethanol for ultrasonic cleaning for 6 minutes, dry it with a hair dryer, and pack it into a bag for later use.

(2) Smelting: Mix the pretreated granular raw materials according to the proportion, among which, industrial pure aluminum accounts for 5wt%, industrial pure tin accounts for 2.5wt%, industrial pure iron accounts for 4wt%, and the rest is sponge titanium. The alloy raw material with a total mass of 50g was put into the water-cooled copper crucible of GDJ500C non-consumable vacuum arc melting furnace, and the cooling water circulation system was used to vacuumize and fill with argon for protection. Each alloy ingot was smelted five times repeatedly to obtain Button ingots.

(3) Structure optimization heat treatment: conduct structure optimization heat treatment on the button ingot obtained from smelting, use argon as the protective atmosphere in a vacuum tube resistance furnace as the heat treatment furnace, heat to 1000 ° C, keep it for 40 minutes, and then cool with the furnace to obtain the final α +β-type duplex titanium-based alloy material.

Example 3

This embodiment provides a dual-phase titanium-based alloy, the preparation method of which is:

(1) Pretreatment: get raw material sponge titanium (purity is 99.95wt%), industrial pure aluminum (purity is 99.99wt%), industrial pure tin (purity is 99.95wt%) and industrial pure iron (carbon content is 0.04wt%) % or less), cut it into several particles with a size of 3mm × 3mm × 3mm by wire cutting technology, place the raw material particles in a mixed solution with a volume ratio of acetone and absolute ethanol of 6:8 for 5 minutes cleaning. Subsequently, the titanium sponge particles are placed in an aqueous solution of hydrofluoric acid and nitric acid to pickle the surface, wherein the volume ratio of hydrofluoric acid, nitric acid and water is 3:3:6; industrial pure iron particles are placed in sulfuric acid The surface is pickled in an aqueous solution, where the volume ratio of sulfuric acid and water is 3:9. After pickling for 90s, place it in absolute ethanol for ultrasonic cleaning for 5 minutes, dry it with a hair dryer, and pack it into a bag for later use.

(2) Smelting: Mix the pretreated granular raw materials according to the proportion, among which, industrial pure aluminum accounts for 3wt%, industrial pure tin accounts for 4wt%, industrial pure iron accounts for 8wt%, and the rest is sponge titanium. The alloy raw material with a mass of 50g is put into the water-cooled copper crucible of GDJ500C non-consumable vacuum arc melting furnace, and the cooling water circulation system is adopted and vacuumized and filled with argon for protection. Each alloy ingot needs to be smelted 5 times repeatedly to obtain buttons ingot.

(3) Structure optimization heat treatment: conduct structure optimization heat treatment on the button ingot obtained by smelting, use argon as the protective atmosphere in a vacuum tube resistance furnace as the heat treatment furnace, heat to 900 ° C, hold for 60 minutes, and then cool with the furnace to obtain the final α +β-type duplex titanium-based alloy material.

Comparative example 1

This embodiment provides a dual-phase titanium-based alloy, the preparation method of which is:

(1) Pretreatment: get raw material sponge titanium (purity is 99.95wt%), industrial pure aluminum (purity is 99.99wt%), industrial pure tin (purity is 99.95wt%) and industrial pure iron (carbon content is 0.04wt%) % or less), cut it into several particles with a size of 1mm × 1mm × 1mm by wire cutting technology, place the raw material particles in a mixed solution with a volume ratio of acetone and absolute ethanol of 2:4 for 10 minutes to treat the surface cleaning. Subsequently, the titanium sponge particles were placed in an aqueous solution of hydrofluoric acid and nitric acid to pickle the surface, wherein the volume ratio of hydrofluoric acid, nitric acid and water was 1:2:3; industrial pure iron particles were placed in sulfuric acid The surface is pickled in an aqueous solution, where the volume ratio of sulfuric acid and water is 1:7. After pickling for 120s, place it in absolute ethanol for ultrasonic cleaning for 8 minutes, dry it with a hair dryer, and pack it into a bag for later use.

(2) Smelting: Mix the pretreated granular raw materials in proportion, among which, industrial pure aluminum accounts for 5wt%, industrial pure tin accounts for 3.7wt%, industrial pure iron accounts for 2wt%, and the rest is sponge titanium. The alloy raw material with a total mass of 50g was put into the water-cooled copper crucible of GDJ500C non-consumable vacuum arc melting furnace, and the cooling water circulation system was used to vacuumize and fill with argon for protection. Each alloy ingot was smelted five times repeatedly to obtain Button ingots.

(3) Structure optimization heat treatment: conduct structure optimization heat treatment on the button ingot obtained by smelting, use argon as the protective atmosphere in a vacuum tube resistance furnace as the heat treatment furnace, heat to 750 ° C, keep it for 10 hours, and then cool with the furnace to obtain the final α +β-type duplex titanium-based alloy material.

Comparative example 2

This embodiment provides a dual-phase titanium-based alloy, the preparation method of which is:

(1) Pretreatment: Take raw material sponge titanium, industrial pure aluminum, industrial pure tin, take an industrial pure iron plate with a size of 50mm×20mm×1mm, and cut it into several pieces with a size of 1mm×1mm×1mm by wire cutting Particles, the raw material particles are placed in a mixed solution of acetone and absolute ethanol with a volume ratio of 2:4 and soaked for 10 minutes to clean the surface. Subsequently, the titanium sponge particles were placed in an aqueous solution of hydrofluoric acid and nitric acid to pickle the surface, wherein the volume ratio of hydrofluoric acid, nitric acid and water was 1:2:3; industrial pure iron particles were placed in sulfuric acid The surface is pickled in an aqueous solution, where the volume ratio of sulfuric acid and water is 1:7. After pickling for 120s, place it in absolute ethanol for ultrasonic cleaning for 8 minutes, dry it with a hair dryer, and pack it into a bag for later use.

(2) Smelting: Mix the pretreated granular raw materials in proportion, among which, industrial pure aluminum accounts for 5wt%, industrial pure tin accounts for 3.7wt%, industrial pure iron accounts for 2wt%, and the rest is sponge titanium. The alloy raw material with a total mass of 50g was put into the water-cooled copper crucible of GDJ500C non-consumable vacuum arc melting furnace, and the cooling water circulation system was used to vacuumize and fill with argon for protection. Each alloy ingot was smelted five times repeatedly to obtain Button ingots.

(3) Structure optimization heat treatment: conduct structure optimization heat treatment on the button ingot obtained by smelting, use argon as the protective atmosphere in a vacuum tube resistance furnace as the heat treatment furnace, heat to 1300 ° C, keep it for 10 minutes, and then cool with the furnace to obtain the final α +β-type duplex titanium-based alloy material.

test

The button ingots obtained by the tissue optimization heat treatment in Examples 1 to 3 and Comparative Example 1 and Comparative Example 2 are cut out of tensile samples as shown in Figure 1 with wire cutting technology, and the tensile test is carried out. Every button ingot is cut at least More than 3 tensile samples were taken to ensure the repeatability of the test results, and a uniaxial tensile test (with an extensometer) was performed using a universal material testing machine model MTS E45, with a tensile rate of 0.375mm/min , and the relevant data of its mechanical properties are obtained as shown in Table 1 and Table 2.

Table 1. Mechanical performance test results of the dual-phase titanium-based alloy material obtained in Examples 1 to 3

The preparation method of the comparative alloy Ti-5Al-2.5Sn-0.15O in Table 1 is to make the chemical composition be 5.6%Al, 2.6%Sn, 0.15%O (mass percentage), the balance is the TA7 of Ti and unavoidable impurity The titanium alloy plate is subjected to heat treatment, and the heat treatment condition is to keep the temperature at 850°C for 45min in a muffle furnace.

Table 2. The mechanical property test results of the dual-phase titanium-based alloy materials obtained in two comparative examples

The X-ray diffraction results of the dual-phase titanium-based alloy obtained in Examples 1-3 are shown in Figure 2, and the microstructure diagrams are shown in Figures 3-5 in sequence.

Figure 2 reflects the phase composition of the dual-phase titanium-based alloys with different Fe contents. From the X-ray diffraction results of the dual-phase titanium-based alloy obtained in Example 1, it can be seen that after the addition of 2% Fe element by mass percentage, the β-phase diffraction peak (111) appears near the 2θ value of 39.6°, indicating that the titanium-based alloy appears beta phase. From the X-ray diffraction results of the dual-phase titanium-based alloys obtained in Examples 2 and 3, it can be seen that after adding 4% and 8% Fe by mass percentage respectively, the titanium-based alloys are still composed of α-phase and β-phase, and With the increase of the mass percentage of Fe element, the intensity of β-phase diffraction peak gradually increases, indicating that the distribution of β-phase in titanium alloy is positively correlated with the mass percentage of Fe element, and Fe element can be used as a stable element of β-phase to reduce the phase transition temperature.

3 to 5 are microstructure diagrams of Examples 1 to 3, respectively. It can be seen from Figure 3 that when the Fe content in the titanium alloy is 2wt%, the alloy is a basket structure. When the Fe content is 4wt% (Figure 4), the size of the α-phase lath becomes smaller, the degree of doping becomes higher, and the α-phase and β-phase are alternately arranged, indicating that the microstructure of the titanium alloy is closely related to the content of the contained Fe element. , the Fe element plays the role of stabilizing the β phase, reduces the transition temperature of the titanium alloy from the α phase to the β phase, and shortens the transition time from the β phase to the α phase during the air cooling process. With the increase of Fe content, the length of the α slab gradually shortens. When the Fe content is 8wt% (Fig. 5), the microstructure of the titanium alloy is no longer a regular basket structure, but obvious β-phase boundaries can be seen, and there are elongated and slender phases in the coarse original β grains. The α slabs show that the stability of β phase in titanium alloy is positively correlated with the content of Fe element. The addition of Fe element makes the α laths tend to be thinner, and the higher the content of Fe element, the more obvious this effect is because the addition of Fe element causes the original β grains to break up during the solidification process of the titanium alloy, which is the foundation for the subsequent The nucleation of the α phase provides enough nucleation sites to achieve the purpose of grain refinement, so that the titanium alloy can be solid-solution strengthened and fine-grained, and better mechanical properties can be obtained.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (9)

1. An Fe-containing dual-phase titanium-based alloy, characterized in that the dual-phase titanium-based alloy comprises the following components in the following mass percentages: Al: 1%-5%, Sn: 2.5%-6%, Fe: 2% to 8%, the balance is Ti and other unavoidable impurities. 2. A kind of Fe-containing dual-phase titanium-based alloy according to claim 1, characterized in that, the raw material of the Al is industrial pure aluminum with a purity of more than 99.9%; and/or The raw material of the Sn is industrial pure tin with a purity of 99.9% or more; and/or The raw material of the Fe is industrial pure iron with a carbon content below 0.04%; and/or The raw material of the Ti is titanium sponge with a purity of 99.9% or more. 3. a method for preparing the dual-phase titanium-based alloy according to claim 1 or 2, characterized in that, according to the mass percentage of the component according to claim 1 or 2, the raw materials of the components are smelted and processed successively Microstructure optimization heat treatment to obtain a dual-phase titanium-based alloy. 4. the preparation method of duplex titanium-based alloy according to claim 3, is characterized in that, the raw material of each component is granular, and described preparation method also comprises using organic solution to clean granular raw material, and with acid solution Fe and Ti raw materials are cleaned. 5. the preparation method of duplex titanium-based alloy according to claim 4, is characterized in that, described organic solution comprises acetone and dehydrated alcohol, and the acid in described acid solution comprises hydrofluoric acid, nitric acid and sulfuric acid at least one. 6 . The method for preparing a duplex titanium-based alloy according to claim 3 , wherein the smelting uses a non-consumable vacuum arc melting furnace, and the protective gas is an inert gas. 7. The method for preparing a dual-phase titanium-based alloy according to claim 3, characterized in that, the structure optimization heat treatment uses a vacuum tube resistance furnace as a heat treatment furnace, and the protective gas is an inert gas. 8 . The method for preparing a dual-phase titanium-based alloy according to claim 3 , wherein the heating temperature of the structure optimization heat treatment is 900° C. to 1100° C. 9 . The method for preparing a dual-phase titanium-based alloy according to claim 8 , characterized in that, the holding time of the heat treatment for structure optimization is 10 minutes to 60 minutes.

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