Preparation method of high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material

Abstract

The present invention discloses a preparation method of a high-toughness Ti-Mo-Si-C supersaturated solid solution alloy material, relating to the technical field of high-toughness structural metal materials. The alloy material is composed of a Ti alloy matrix and Mo, Si and C alloying elements, and the alloying elements are distributed in the titanium alloy matrix as interstitial solid solution and substitutional solid solution elements; the composition mass percentage of the alloying elements is: Mo: 0-30%, Si: 0-10%, C: 0-10%, and the rest is Ti; the high-toughness Ti-Mo-Si-C supersaturated solid solution alloy material is prepared by low-energy ball milling, spark plasma sintering combined with high-temperature hot rolling and annealing treatment of raw materials; the high-toughness Ti-Mo-Si-C supersaturated solid solution alloy material prepared by the present invention, during the deformation process, it produces synergistic effects such as solid solution strengthening effect, fine grain strengthening effect, phase transformation strengthening effect, etc., so that the strength (ultimate tensile strength and yield strength) and plasticity of the titanium alloy can be greatly improved at the same time, so that the tensile strength of the alloy material can reach more than 1300MPa and the elongation is greater than 8%.

Description

Technical Field

[0001] The invention relates to a preparation method of a high-strength and toughness Ti-Mo-Si-C supersaturated solid solution alloy material, belonging to the field of high-strength and toughness structural metal materials. Background Art

[0002] Titanium-based composites, due to their low density, high specific strength, and excellent high-temperature service performance, have found wider applications in aerospace and weaponry applications compared to high-temperature titanium alloys. TiC and Ti5Si3 not only possess good chemical compatibility with the Ti matrix but also exhibit excellent high-temperature oxidation resistance, making them considered ideal reinforcement phases for developing high-temperature titanium-based composites. Numerous studies have shown that the high-temperature service temperature of titanium-based composites is closely related to the content and distribution of the TiC and Ti5Si3 reinforcement phases, with the high-temperature service temperature gradually increasing with increasing reinforcement content. However, when the addition of C and Si exceeds 0.1wt.% and 0.4wt.%, coarse TiC and Ti5Si3 reinforcement phases form at the matrix interface during sintering and densification, resulting in a sharp decrease in the composite's strength and toughness, making it unable to meet the requirements of structural materials. Therefore, overcoming the inverse relationship between the room-temperature mechanical properties and high-temperature oxidation resistance of titanium-based composites is of great significance to the development of the aerospace industry.

[0003] Supersaturated solid solution is considered to be an effective method to improve the room temperature mechanical properties of materials without deteriorating high temperature properties. For example, researchers such as Li prepared Cu core / Ag shell materials with supersaturated solid solution structure, which increased the ultimate oxidation resistance temperature (150°C) of traditional Cu core-Ag shell materials and Cu / Ag composite materials to 220°C, while maintaining good room temperature mechanical properties. In order to achieve supersaturated solid solution, mechanical alloying is considered to be a feasible technical means. According to literature reports, mechanical alloying can greatly expand the solid solubility of binary systems, and can even achieve solid solubility of immiscible systems. The research results of Rafiei et al. show that the solid solubility of Al in W can be increased from 15.9% to more than 50% (atomic fraction) by mechanical alloying.

[0004] However, there are two major problems in achieving supersaturated solid solution in titanium alloys using mechanical alloying technology, which limit its development: First, a large amount of impurity elements will be introduced into the titanium alloy powder during the mechanical alloying process, making the alloy powder brittle; second, a large number of unstable lattice defects will be generated inside the powder during the mechanical alloying process, which will promote the dissolution of solid solution elements and even form grain boundary precipitation phases at the grain boundaries during subsequent sintering or heat treatment. These two factors ultimately lead to a mismatch in the room temperature mechanical properties (strength-toughness) of titanium alloys, making it difficult to ensure the safety and reliability of high-temperature titanium alloys in service environments. Therefore, how to achieve breakthroughs in preparation technology and solve the problem of mismatch in the room temperature mechanical properties of titanium alloys is a key bottleneck problem that urgently needs to be solved in the application and development of titanium alloys in the field of aerospace technology. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the object of the present invention is to provide a method for preparing a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material, which combines hot rolling and annealing to make Mo and Si distributed in the alloy matrix as a supersaturated substitutional solid solution, and C distributed in the alloy matrix as a supersaturated interstitial solid solution. The method specifically comprises the following steps:

[0006] (1) Nano-SiC particles and Ti, Mo powder or Si, C, Ti and Mo powder are weighed according to the composition ratio, mixed evenly using a planetary ball mill, and dried to obtain a uniformly mixed Ti-Mo-Si-C composite powder.

[0007] (2) The composite powder is subjected to spark plasma sintering, hot rolling and annealing to obtain a Ti-Mo-Si-C supersaturated solid solution alloy material.

[0008] Preferably, the mass percentages of the alloy components of the present invention are: Mo: 0-30%, and not 0; Si: 0-10%, and not 0; C: 0-10%, and not 0; and the rest is Ti.

[0009] Preferably, the ball milling process parameters in step (1) of the present invention are: ball-to-material ratio of 5:1 to 10:1, rotation speed of 200 to 500 r / min, ball milling time of 2 to 24 h, and wet milling using anhydrous ethanol as solvent.

[0010] Preferably, in the spark plasma sintering process in step (2) of the present invention, the sintering temperature is 900-1500° C., the holding time is 5-30 min, and the pressure is 5-50 MPa.

[0011] Preferably, the hot rolling process conditions in step (2) of the present invention are: a temperature of 750-1200° C., after keeping the temperature within this temperature range for 10-120 minutes, the hot rolling process is carried out, and the total reduction amount is 40-90%.

[0012] Preferably, the annealing process conditions in step (2) of the present invention are: temperature of 500-800° C., and time of 0.5-2 h.

[0013] Preferably, the alloy material of the present invention is composed of Ti and Mo, Si and C alloy elements, and C in the alloy element is distributed in the alloy matrix as a supersaturated interstitial solid solution; during the deformation process of the alloy material, the synergistic effects of the solid solution strengthening effect, the fine grain strengthening effect, the phase transformation strengthening effect, etc. are produced, so that the strength of the alloy material can reach more than 1300MPa and the plasticity is greater than 8%.

[0014] The method described in the present invention gradually increases the solid solubility of C and Si elements in the Ti alloy as the temperature increases. High-temperature deformation combined with quenching technology is used to promote the dissolution of coarse TiC and Ti5Si3 reinforcing phases at the grain boundaries, achieve supersaturated solid solution of C and Si elements in the Ti alloy at room temperature, and suppress the occurrence of strength-ductility inversion phenomenon of TiC and Ti5Si3 reinforced titanium-based composite materials. In addition, hot deformation is one of the most effective methods to avoid strength-ductility mismatch of titanium alloys by regulating the size and phase transformation of titanium alloys.

[0015] The present invention has made a breakthrough in the preparation technology of supersaturated solid solution Ti-Mo-Si-C alloy materials. Hot rolling technology is used to promote element diffusion, so that coarse TiC and Ti5Si3 ceramic phases are decomposed below the solvus temperature. The quenching process inhibits the diffusion of elements, thereby preparing a Ti supersaturated solid solution structure containing 0-10wt.% Si and 0-10wt.% C. At the same time, during the hot rolling process, high strain accumulation causes the lamellar α-Ti to be refined. Compared with the sintered material, the ultimate tensile strength and elongation at break of the hot-rolled material are increased from 1101MPa and 2.2% to 1234MPa and 4.8%, respectively. More importantly, under the 500-800℃ annealing process, thanks to the fast diffusion rate of the C element, a relatively sufficient nano-sized α-Ti secondary phase can be precipitated during the annealing process, so that the alloy obtains an ultimate tensile strength of up to 1300MPa while maintaining an elongation of 9.6%.

[0016] Beneficial effects of the present invention:

[0017] The alloy material of the present invention uses low-energy ball milling to achieve uniform mixing of Ti, Mo, Si, C powders or Ti, Mo, SiC powders, solving the technical problem of brittleness caused by the introduction of impurities during the preparation of supersaturated solid solution materials by traditional mechanical alloying methods.

[0018] During the deformation process, the high-strength and toughness Ti-Mo-Si-C supersaturated solid solution alloy material of the present invention produces a synergistic effect of solid solution strengthening effect, fine grain strengthening effect, phase transformation strengthening effect, etc., thereby significantly improving the strengthening (ultimate tensile strength and yield strength) and ductility of the titanium alloy at the same time, so that the strength of the alloy material can reach more than 1300MPa and the plasticity is greater than 8%; at the same time, the method effectively reduces the equipment and energy consumption requirements, and is more suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the preparation process of the high-strength and toughness Ti-Mo-Si-C supersaturated solid solution alloy material of the present invention;

[0020] Figure 2 The microstructure evolution of the high-strength and toughness Ti-Mo-Si-C supersaturated solid solution alloy material of the present invention during sintering, rolling and annealing.

[0021] Figure 3 This is the room temperature tensile property curve of the high-strength and toughness Ti-Mo-Si-C supersaturated solid solution alloy material of the present invention under sintering, rolling and annealing conditions. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0023] In the embodiment of the present invention, Figure 1 As shown, the preparation process of the high-strength and toughness Ti-Mo-Si-C supersaturated solid solution alloy material of the present invention includes: low-energy ball milling, spark plasma sintering, hot rolling and annealing. The raw materials are mixed evenly by low-energy ball milling, and a reaction as shown in formula (1) occurs during rapid sintering. Then, a supersaturated solid solution structure is formed inside the titanium alloy matrix through hot rolling and annealing.

[0024] 8Ti+3SiC=Ti5Si3+3TiC (1)

[0025] Example 1

[0026] A method for preparing a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material specifically comprises the following steps:

[0027] S1: The alloy raw materials Mo, Si, C powder and Ti powder were mixed. 10g Mo powder, 10g Si powder, 10g C powder and 70g Ti powder were weighed respectively, and mixed evenly using a planetary ball mill with a ball-to-material ratio of 5:1, a rotation speed of 200r / min, and a ball milling time of 24h. Anhydrous ethanol was used as a mixing agent. The mixed powder was dried in a vacuum drying oven to obtain a Ti-Mo-Si-C composite powder.

[0028] S2: The composite powder is subjected to spark plasma sintering at a sintering temperature of 900°C, a holding time of 30 minutes, and a pressure of 40 MPa. It is then hot-rolled at 1200°C for 10 minutes, with a single-pass reduction of 15% and a total reduction of 40%. It is then annealed in a muffle furnace at 500°C for 2 hours. The microstructures of the hot-rolled and annealed state are shown in FIG. Figure 2 As shown; a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material is obtained, which makes the ultimate tensile strength of the alloy as high as 1301MPa and the elongation at break reach 9.6%.

[0029] Example 2

[0030] A method for preparing a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material specifically comprises the following steps:

[0031] S1: The alloy raw materials Mo, Si, C powder and Ti powder were mixed. 5g Mo powder, 5g Si powder, 5g C powder and 85g Ti powder were weighed respectively and mixed evenly in a planetary ball mill with a ball-to-material ratio of 5:1, a rotation speed of 300r / min, and a ball milling time of 4h. Anhydrous ethanol was used as a mixing agent. The mixed powder was dried in a vacuum drying oven to obtain Ti-Mo-Si-C composite powder.

[0032] S2: The composite powder is subjected to spark plasma sintering at a sintering temperature of 1200°C, a holding time of 10 min, and a pressure of 45 MPa to prepare a (TiC+Ti5Si3) / Ti-Mo composite material, wherein the TiC reinforcement phase has a coarse grain size and is distributed at the grain boundary; the composite powder is then hot rolled after being held at 850°C for 30 min, with a single-pass reduction of 20% and a total reduction of 60%, wherein the coarse TiC reinforcement phase and Ti5Si3 are separated to form a supersaturated solid solution titanium alloy; the composite powder is then annealed in a muffle furnace at 600°C for 0.5 h, wherein a large amount of dispersed nano-sized α-Ti is precipitated in the β-Ti. s phase; obtain high strength and toughness Ti-Mo-Si-C supersaturated solid solution alloy material; the measured mechanical properties of the alloy are as follows: ultimate tensile strength is as high as 1727MPa, and elongation at break is 6%.

[0033] Example 3

[0034] A method for preparing a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material specifically comprises the following steps:

[0035] S1: The alloy raw materials Mo, SiC powder and Ti powder were mixed. 10g Mo powder, 15g SiC powder and 75g Ti powder were weighed respectively and mixed evenly in a planetary ball mill with a ball-to-material ratio of 10:1, a rotation speed of 500r / min, and a ball milling time of 2h. Anhydrous ethanol was used as a mixing agent. The mixed powder was dried in a vacuum drying oven to obtain a Ti-Mo-Si-C composite powder.

[0036] S2: The composite powder is subjected to spark plasma sintering at a sintering temperature of 1500°C, a holding time of 5 minutes, and a pressure of 5 MPa, and then hot rolled at 750°C for 120 minutes, with a single-pass reduction of 10% and a total reduction of 90%; then annealed in a muffle furnace at 800°C for 1 hour to obtain a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material; the measured mechanical properties of the alloy are as follows: the ultimate tensile strength is as high as 1380 MPa, and the elongation at break is 6%.

[0037] Example 4

[0038] A method for preparing a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material specifically comprises the following steps:

[0039] S1: The alloy raw materials Mo, SiC powder and Ti powder were mixed. 7g Mo powder, 3g SiC powder and 90g Ti powder were weighed respectively and mixed evenly in a planetary ball mill with a ball-to-material ratio of 5:1, a rotation speed of 300r / min, and a ball milling time of 4h. Anhydrous ethanol was used as a mixing agent. The mixed powder was dried in a vacuum drying oven to obtain a Ti-Mo-Si-C composite powder.

[0040] S2: The composite powder is subjected to spark plasma sintering at a sintering temperature of 1100°C, a holding time of 15 minutes, and a pressure of 50 MPa, and then hot rolled after holding at 900°C for 30 minutes, with a single-pass reduction of 15% and a total reduction of 70%; then annealed in a muffle furnace at 650°C for 2 hours; a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material is obtained; the measured mechanical properties of the alloy are as follows: the ultimate tensile strength is as high as 1365 MPa, and the elongation at break is 4.5%.

[0041] Example 5

[0042] A method for preparing a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material specifically comprises the following steps:

[0043] S1: The alloy raw materials Mo, SiC powder and Ti powder were mixed. 5g Mo powder, 3g SiC powder and 92g Ti powder were weighed respectively and mixed evenly using a planetary ball mill with a ball-to-material ratio of 7:1, a rotation speed of 400r / min, and a ball milling time of 4h. Anhydrous ethanol was used as a mixing agent. The mixed powder was dried in a vacuum drying oven to obtain a Ti-Mo-Si-C composite powder.

[0044] S2: The composite powder is subjected to spark plasma sintering at a sintering temperature of 1200°C, a holding time of 15 minutes, and a pressure of 50 MPa, and then hot rolled at 900°C for 30 minutes, with a single-pass reduction of 15% and a total reduction of 70%; then annealed in a muffle furnace at 750°C for 1 hour to obtain a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material.

[0045] Comparative Example 1

[0046] A method for preparing a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material specifically comprises the following steps:

[0047] S1: According to the elemental components of Example 1, the corresponding powders were weighed and mixed uniformly using a planetary ball mill with a ball-to-material ratio of 5:1, a rotation speed of 300 r / min, and a ball milling time of 4 h. Anhydrous ethanol was used as a mixing agent. The mixed powder was dried in a vacuum drying oven to obtain a Ti-Mo-Si-C composite powder;

[0048] S2: The composite powder was subjected to spark plasma sintering at a sintering temperature of 900°C, a holding time of 30 minutes, and a pressure of 40 MPa. The microstructure thereof consisted of a coarse TiC reinforcement phase distributed at the grain boundaries, a dispersed Ti5Si3 reinforcement phase, and a titanium matrix with a Widmanstätten structure. The mechanical properties of the sample were measured as follows: Figure 3 In comparative example 1, the ultimate tensile strength is 1101 MPa and the elongation at break is 2.2%. It can be seen that, compared with Example 1, the performance of the sample in which the composite powder is subjected to spark plasma sintering but not subsequent hot rolling and annealing treatment is poor, mainly because the C and Si elements do not form a supersaturated solid solution, but are distributed at the interface of the titanium alloy in the form of coarse TiC and Ti5Si3 reinforcement phases, becoming the source of cracks.

[0049] Comparative Example 2

[0050] A method for preparing a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material specifically comprises the following steps:

[0051] S1: According to the elemental components of Example 1, the corresponding powders were weighed respectively and mixed evenly using a planetary ball mill with a ball-to-material ratio of 5:1, a rotation speed of 200 r / min, a ball milling time of 24 h, and anhydrous ethanol as a mixing agent. The mixed powder was dried in a vacuum drying oven to obtain a Ti-Mo-Si-C composite powder.

[0052] S2: The composite powder was subjected to spark plasma sintering at a sintering temperature of 900°C, a holding time of 30 minutes, and a pressure of 40 MPa. The composite powder was then hot rolled at 1200°C for 10 minutes, with a single-pass reduction of 15% and a total reduction of 40%. The composite powder was then annealed in a muffle furnace at 850°C for 2 hours to obtain a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material. The microstructure of the alloy material consisted of coarse α-Ti and β-Ti containing supersaturated C, Mo, and Si solid solution elements. The mechanical properties of the sample were measured as follows: Figure 3 In comparative example 2, the ultimate tensile strength is 1130 MPa and the elongation at break is 1.3%. It can be seen that the excessively high annealing temperature compared with that in example 1 causes abnormal growth of the titanium matrix grains, and the mechanical properties of the alloy are very poor, making it difficult to apply the alloy in industry.

[0053] Comparative Example 3

[0054] A method for preparing a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material specifically comprises the following steps:

[0055] S1: According to the elemental components of Example 2, the corresponding powders were weighed respectively and mixed evenly using a planetary ball mill with a ball-to-material ratio of 5:1, a rotation speed of 300 r / min, a ball milling time of 4 h, and anhydrous ethanol as a mixing agent. The mixed powder was dried in a vacuum drying oven to obtain a Ti-Mo-Si-C composite powder.

[0056] S2: The composite powder was subjected to spark plasma sintering at a sintering temperature of 1200°C, a holding time of 10 minutes, and a pressure of 45 MPa. The composite powder was then hot rolled at 700°C for 30 minutes, with a single-pass reduction of 15% and a total reduction of 60%. The composite powder was then annealed in a muffle furnace at 650°C for 2 hours. The microstructure of the composite powder consisted of coarse TiC reinforcement phases that were not completely decomposed and α-Ti and β-Ti containing supersaturated Mo and Si solid solution elements. The mechanical properties of the sample were measured as follows: Figure 3 In Comparative Example 3, the ultimate tensile strength is 1130 MPa and the elongation at break is 1.3%. It can be seen that the rolling temperature is too low to completely decompose the coarse TiC reinforcing phase, and the C element cannot form a supersaturated solid solution structure in the Ti alloy. The coarse TiC reinforcing phase is still distributed at the interface of the Ti alloy matrix and becomes a crack source. The mechanical properties of the alloy are very poor, making it difficult to apply it in industry.

Claims

1. A method for preparing a high-strength and tough Ti-Mo-Si-C supersaturated solid solution alloy material, characterized by: Combining hot rolling and annealing, Mo and Si are distributed in the alloy matrix as supersaturated substitutional solid solution, and C is distributed in the alloy matrix as supersaturated interstitial solid solution, which specifically includes the following steps: (1) weighing nano-SiC particles and Ti, Mo powder or Si, C, Ti and Mo powder according to the composition ratio, mixing them uniformly using a planetary ball mill, and drying to obtain a uniformly mixed Ti-Mo-Si-C composite powder; (2) subjecting the composite powder to spark plasma sintering, hot rolling and annealing to obtain a Ti-Mo-Si-C supersaturated solid solution alloy material; The mass percentage of the alloy components is Mo: 0-30%, and not 0; Si: 0-10%, and not 0; C: 0-10%, and not 0; the rest is Ti; The hot rolling process conditions in step (2) are as follows: the temperature is 750-1200°C, and after keeping the temperature within the temperature range for 10-120 minutes, the hot rolling process is carried out, and the total rolling amount is 40-90%; The annealing process conditions in step (2) are: temperature of 500-800° C. and time of 0.5-2 h.

2. The method for preparing the high-strength and toughness Ti-Mo-Si-C supersaturated solid solution alloy material according to claim 1, characterized in that: The ball milling process parameters in step (1) are: ball-to-material ratio of 5:1 to 10:1, rotation speed of 200 to 500 r / min, ball milling time of 2 to 24 hours, and wet milling with anhydrous ethanol as solvent.

3. The method for preparing the high-strength and toughness Ti-Mo-Si-C supersaturated solid solution alloy material according to claim 1, characterized in that: During the spark plasma sintering process in step (2), the sintering temperature is 900-1500° C., the holding time is 5-30 minutes, and the pressure is 5-50 MPa.

4. The Ti-Mo-Si-C supersaturated solid solution alloy material prepared by the method according to any one of claims 1 to 3, characterized in that: The alloy material consists of Ti and Mo, Si and C alloy elements, and C among the alloy elements is distributed in the alloy matrix in the form of supersaturated interstitial solid solution.

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