CN117107111A - A high-strength and tough titanium alloy and its preparation method - Google Patents

Abstract

The invention discloses a high-strength and high-toughness titanium alloy and a preparation method thereof, wherein the titanium alloy comprises the following chemical components in percentage by mass: ti:92.5% -97.5%, crMnFeCoNi:2.5% -7.5%, and the balance is unavoidable impurity elements, and the preparation method comprises the following steps: firstly, ball-milling and mixing raw material powder, and then performing spark plasma sintering molding to obtain a titanium alloy sintered body with reinforcing phases in quasi-continuous distribution along grain boundaries. The alloy has better plastic deformation capacity and greatly improves the tensile strength; the titanium alloy prepared by the method has low cost and simple process, and the obtained titanium alloy has excellent toughness.

Description

A high-strength and tough titanium alloy and its preparation method

Technical field

The invention belongs to the field of titanium alloys and relates to a high-strength and tough powder metallurgy titanium alloy and a preparation method thereof.

Background technique

Titanium and titanium alloys are important structural metal materials with many excellent properties, such as high specific strength, low density, excellent corrosion resistance and high temperature resistance, good processability, etc., and are widely used in aerospace , chemical industry, biomedicine and many other fields, it is known as the modern metal of the 21st century.

It is mentioned in the literature (PANIGRAHI B B. Sintering behavior of Ti–2Ni and Ti–5Nielemental powders [J]. Materials Letters, 2007, 61(1): 152-5) that low density is prone to occur when preparing titanium alloys by powder metallurgy. , unconverted particle interfaces and defects such as holes. These defects will have a greater impact on the plasticity of the material. For example, the room temperature elongation of powder metallurgy TC4 titanium alloy is usually less than 8%.

Contents of the invention

In view of the current shortcomings of complex preparation processes and poor mechanical properties of titanium and titanium alloy materials, the present invention proposes a HEA-Ti series titanium alloy with high strength and toughness. The titanium alloy has a simple preparation process and excellent mechanical properties.

The present invention is realized through the following technical solutions:

A high-strength titanium alloy and its preparation method. Its chemical composition in mass percentage is: Ti: 92.5%~97.5%, CrMnFeCoNi: 2.5%~7.5%, and the rest are unavoidable impurity elements;

Specifically, it includes the following steps:

(1) Configure the raw materials required for titanium alloy according to the designed composition and mix them evenly by ball milling;

(2) In a vacuum environment, the raw materials configured in step (1) are subjected to discharge plasma sintering, and the principle of continuous instantaneous liquid phase sintering is used to obtain a titanium alloy sintered body in which the reinforcement phase is quasi-continuously distributed along the particle boundaries.

Preferably, in step (1), the Ti powder and CrMnFeCoNi powder required for the titanium alloy are prepared according to the designed composition.

Preferably, in step (2), the temperature rise rate of discharge plasma sintering is 50°C/min, the sintering temperature is 1050~1150°C, the holding time is 2 minutes, and the cooling method of furnace cooling is adopted.

Preferably, the room temperature tensile strength of the titanium alloy prepared by spark plasma sintering exceeds 700MPa, and the plastic deformation exceeds 12.5%.

Compared with the prior art, the beneficial effects of the present invention are:

(1) This alloy has good plastic deformation ability and greatly increases the tensile strength. When the titanium alloy is sintered, the room temperature tensile strength is greater than 700MPa, and the plastic deformation amount exceeds 12.5%.

(2) The titanium alloy provided by the present invention has good performance, low cost and simple preparation process.

Description of drawings

Figure 1 is a microstructure diagram of Example 1.

Figure 2 is a microstructure diagram of Example 2.

Figure 3 is a microstructure diagram of Example 3.

Detailed ways

In order to better understand the technical content of the present invention, specific embodiments are described below along with the accompanying drawings.

Aspects of the invention are described herein with reference to the accompanying drawings, in which a number of illustrated embodiments are shown. Embodiments of the invention are not necessarily intended to include all aspects of the invention. It is to be understood that the various concepts and embodiments described above, as well as those described in greater detail below, may be implemented in any of many ways, as the disclosed concepts and embodiments do not limited to any implementation. Additionally, some aspects of the present disclosure may be used alone or in any suitable combination with other aspects of the present disclosure.

The invention provides a high-strength HEA-Ti series titanium alloy. A small amount of CrMnFeCoNi high-entropy alloy powder is added to the titanium alloy to produce a quasi-continuously distributed strengthening phase surrounding the titanium matrix particle boundaries, which maintains good performance. The plasticity also greatly improves the tensile strength of titanium alloy. The specific reason is: during the alloy deformation process, after the elastic stage is over, as the stress further increases, local deformation bands appear in the material structure and expand rapidly. If there are no other conditions to hinder it, plastic instability will occur quickly. However, the actual existence of micron-scale precipitated phases enhances the work hardening ability. When the deformation band in the alloy structure expands to the precipitated phase, it is inhibited and difficult to continue to expand. This suppresses the overall plastic instability of the material and forms more new ones. deformation zone, thereby improving the plasticity of the alloy.

The chemical composition of the HEA-Ti series titanium alloy with high strength and toughness according to the present invention is based on mass percentage: Ti powder: 92.5%~97.5%, CrMnFeCoNi powder (purchased from Hebei Qinbang New Materials Co., Ltd.): 2.5%~7.5% , and the rest are unavoidable impurity elements. First, the raw materials required for the titanium alloy are configured according to the designed composition and ball-milled to mix them evenly. Then, the discharge plasma sintering method is used to obtain a high-strength and tough titanium alloy material with a quasi-continuous network distribution of the reinforced phase. The discharge plasma sintering heating rate is 50°C/min, the sintering temperature is 1050~1150°C, the holding time is 2min, and the cooling method is furnace cooling.

Comparative example 1:

Pure titanium material contains inevitable impurity elements.

The preparation method of the pure titanium material is as follows: first, ball milling the pure titanium powder, and then using discharge plasma sintering to prepare the sample. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50°C/min, the sintering temperature is 1100°C, the holding time is 2min, and the furnace is cooled.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature. The results showed that the tensile strength of pure titanium material was 382MPa and the plastic deformation was 39.4%. The material density was measured to be 87.2%.

Comparative example 2:

A titanium alloy material whose chemical composition in mass percentage is: Ti: 92.5%, AlCoCrFeNi _2.1 : 7.5%, and the rest are unavoidable impurity elements.

The preparation method of the titanium alloy material is as follows: first, the raw material powder is ball milled and mixed, and then the sample is prepared by discharge plasma sintering. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50°C/min, the sintering temperature is 1100°C, the holding time is 2min, and the furnace is cooled. The material density was measured to be 92.2%.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature, and the results showed that the tensile strength of the alloy material was 474MPa and the plastic deformation was 8.4%.

Comparative example 3:

A titanium alloy material whose chemical composition in mass percentage is: Ti: 98.0%, CrMnFeCoNi: 2.0%, and the rest are unavoidable impurity elements.

The preparation method of the alloy material is as follows: first, the raw material powder is ball milled and mixed, and then the sample is prepared by discharge plasma sintering. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50°C/min, the sintering temperature is 1100°C, the holding time is 2min, and the furnace is cooled.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature, and the results showed that the tensile strength of the alloy material was 524MPa and the plastic deformation was 19.2%.

Comparative example 4:

A titanium alloy material whose chemical composition in mass percentage is: Ti: 92.0%, CrMnFeCoNi: 8.0%, and the rest are unavoidable impurity elements.

The preparation method of the alloy material is as follows: first, the raw material powder is ball milled and mixed, and then the sample is prepared by discharge plasma sintering. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50°C/min, the sintering temperature is 1100°C, the holding time is 2min, and the furnace is cooled.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature, and the results showed that the tensile strength of the alloy material was 425MPa and the plastic deformation was 3.2%.

Comparative example 5:

A titanium alloy material whose chemical composition in mass percentage is: Ti: 92.5%, CrMnFeCoNi: 7.5%, and the rest are unavoidable impurity elements.

The preparation method of the alloy material is as follows: first, the raw material powder is ball milled and mixed, and then the sample is prepared by discharge plasma sintering. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50°C/min, the sintering temperature is 900°C, the holding time is 2min, and the furnace is cooled.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature, and the results showed that the tensile strength of the alloy material was 322MPa and the plastic deformation was 3.4%.

Comparative example 6:

A titanium alloy material whose chemical composition in mass percentage is: Ti: 92.5%, CrMnFeCoNi: 7.5%, and the rest are unavoidable impurity elements.

The preparation method of the alloy material is as follows: first, the raw material powder is ball milled and mixed, and then the sample is prepared by discharge plasma sintering. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50℃/min, the sintering temperature is 1200℃, the holding time is 2min, and the furnace is cooled.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature. The results showed that the tensile strength of the alloy material was 682MPa and the plastic deformation was 11.3%.

Example 1:

A high-strength powder metallurgy titanium alloy, its chemical composition in mass percentage is: Ti: 97.5%, CrMnFeCoNi: 2.5%, and the rest are unavoidable impurity elements.

The preparation method of the titanium alloy material is as follows: first, the raw material powder is ball milled and mixed, and then discharge plasma sintering is used to prepare the titanium alloy. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50°C/min, the sintering temperature is 1100°C, the holding time is 2min, and the furnace is cooled.

The central part of the sintered sample was cut by wire cutting to make a metallographic sample. After rough grinding, fine grinding, polishing and corrosion, it was observed that the microstructure of the alloy consists of an α-titanium matrix and a granular β-reinforced phase, as shown in the attached figure. 1 shown. During the sintering process of the alloy, the two powders first form a liquid phase to fill the pores between the powders, and gradually form a reinforcing phase at the boundary around the titanium matrix.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature, and the results showed that the tensile strength of the alloy material was 701MPa and the plastic deformation was 15.8%.

Example 2:

A high-strength titanium alloy, its chemical composition in mass percentage is: Ti: 95.0%, CrMnFeCoNi: 5%, and the rest are unavoidable impurity elements.

The preparation method of the titanium alloy material is as follows: first, the raw material powder is ball milled and mixed, and then discharge plasma sintering is used to prepare the titanium alloy. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50°C/min, the sintering temperature is 1100°C, the holding time is 2min, and the furnace is cooled.

The central part of the sintered sample was cut by wire cutting to make a metallographic sample. After rough grinding, fine grinding, polishing and corrosion, it was observed that the microstructure of the alloy consists of an α-titanium matrix and a granular β-reinforced phase, as shown in the attached figure. 2 shown. During the sintering process of the alloy, the two powders first form a liquid phase to fill the pores between the powders, and gradually form a reinforcing phase at the boundary to surround the titanium matrix, forming a quasi-continuously distributed network structure.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature. The results showed that the tensile strength of the alloy material was 712MPa and the plastic deformation was 14.3%.

Example 3:

A high-strength titanium alloy whose chemical composition in mass percentage is Ti: 92.5%, CrMnFeCoNi: 7.5%, and the rest are unavoidable impurity elements.

The preparation method of the titanium alloy material is as follows: first, the raw material powder is ball milled and mixed, and then discharge plasma sintering is used to prepare the titanium alloy. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50°C/min, the sintering temperature is 1100°C, the holding time is 2min, and the furnace is cooled.

The central part of the sintered sample was cut by wire cutting to make a metallographic sample. After rough grinding, fine grinding, polishing and corrosion, it was observed that the microstructure of the alloy consists of an α-titanium matrix and a granular β-reinforced phase, as shown in the attached figure. 3 shown. During the sintering process of the alloy, the two powders first form a liquid phase to fill the pores between the powders, and gradually form a reinforcing phase at the boundary to surround the titanium matrix, forming a quasi-continuously distributed network structure.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature, and the results showed that the tensile strength of the alloy material was 735MPa and the plastic deformation was 13.6%. The density of the material was measured to be 97.8%.

Example 4:

A high-strength titanium alloy whose chemical composition in mass percentage is Ti: 92.5%, CrMnFeCoNi: 7.5%, and the rest are unavoidable impurity elements.

The preparation method of the titanium alloy material is as follows: first, the raw material powder is ball milled and mixed, and then discharge plasma sintering is used to prepare the titanium alloy. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50°C/min, the sintering temperature is 1050°C, the holding time is 2min, and the furnace is cooled.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature. The results showed that the tensile strength of the alloy material was 727MPa and the plastic deformation was 12.8%.

Example 5:

A high-strength titanium alloy whose chemical composition in mass percentage is Ti: 92.5%, CrMnFeCoNi: 7.5%, and the rest are unavoidable impurity elements.

The preparation method of the titanium alloy material is as follows: first, the raw material powder is ball milled and mixed, and then discharge plasma sintering is used to prepare the titanium alloy. Among them, the sintering process is carried out in a vacuum environment, the heating rate is 50℃/min, the sintering temperature is 1150℃, the holding time is 2min, and the furnace is cooled.

Use wire cutting to cut the center of the sintered sample to prepare a standard tensile specimen. Tensile experiments were conducted at room temperature, and the results showed that the tensile strength of the alloy material was 715MPa and the plastic deformation was 12.5%.

Claims (5)

1. The preparation method of the high-strength and high-toughness titanium alloy comprises the following chemical components in percentage by mass: ti:92.5% -97.5%, crMnFeCoNi:2.5% -7.5%;

the method specifically comprises the following steps:

(1) Preparing raw materials required by titanium alloy according to alloy components, and ball-milling and uniformly mixing;

(2) And (3) performing spark plasma sintering on the mixed powder obtained in the step (1) in a vacuum environment to obtain a titanium alloy sintered body with reinforcing phases in quasi-continuous distribution along grain boundaries.

2. The method of claim, wherein in step (1), ti powder and CrMnFeCoNi powder required for the titanium alloy are prepared according to the alloy composition.

3. The method of claim, wherein in the step (2), the temperature rise rate of the spark plasma sintering is 50 ℃/min, the sintering temperature is 1050-1150 ℃, the heat preservation time is 2min, and a cooling mode of cooling along with a furnace is adopted.

4. A high strength and toughness titanium alloy prepared by the method of any one of claims 1-3.

5. The high strength and toughness titanium alloy according to claim 4, wherein the titanium alloy has a room temperature tensile strength exceeding 700MPa and a plastic deformation exceeding 12.5%.