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CN-121976090-A - Rare earth modified casting high-temperature titanium alloy and preparation method and application thereof

CN121976090ACN 121976090 ACN121976090 ACN 121976090ACN-121976090-A

Abstract

The invention discloses a rare earth modified cast high-temperature titanium alloy and a preparation method and application thereof, and belongs to the technical field of high-temperature titanium alloys. The alloy comprises ：Al 5.50%～6.50%,Sn 3.50%～5.00%,Zr 3.50%～5.00%,Mo 0.20%～0.80%,Si 0.10%～0.30%,Nb 0.25%～0.55%,Ta 0.20%～0.40%,W 0.40%～0.60%,Nd 0.25%～0.35%, mass percent of Ti and impurities in balance. By adding the narrow-interval rare earth Nd, the effective Al equivalent of the alpha phase is reduced by utilizing the synergistic effect of tissue purification and dispersion strengthening of the rare earth Nd, so that the precipitation and growth of the brittle ordered phase of Ti 3 Al in the high-temperature long-time service process are obviously inhibited. The preparation method comprises a vacuum smelting and innovative five-stage hot isostatic pressing process, and the process realizes densification, homogenization and tissue stabilization integrated treatment through programmed temperature and pressure regulation. The obtained alloy has excellent high-temperature strength, plasticity and long-time structure stability at the temperature of 650 ℃ and above, and is suitable for high-temperature structural parts of aeroengines and gas turbines.

Inventors

  • LIU PEI
  • Wei Xuekun
  • ZHAO YANCHANG
  • WANG ZHIZHI
  • XIE JINGPEI
  • WANG AIQIN
  • LIANG TINGTING

Assignees

  • 河南科技大学

Dates

Publication Date
20260505
Application Date
20260206

Claims (6)

  1. 1. The rare earth modified cast high-temperature titanium alloy is characterized by comprising the following components ：Al 5.50%～6.50%,Sn 3.50%～5.00%,Zr 3.50%～5.00%,Mo 0.20%～0.80%,Si 0.10%～0.30%,Nb 0.25%～0.55%,Ta 0.20%～0.40%,W 0.40%～0.60%,Nd 0.25%～0.35%, by mass percent, wherein the balance is Ti and unavoidable impurity elements; Wherein, through the addition of Nd element, the tissue purification and dispersion strengthening are realized to inhibit the precipitation of Ti 3 Al ordered phase.
  2. 2. The rare earth modified cast high temperature titanium alloy according to claim 1, wherein the alloy comprises, by mass, 5.9% of Al, 4.5% of Sn, 4.0% of Zr, 0.5% of Mo, 0.2% of Si, 0.4% of Nb, 0.3% of Ta, 0.5% of W, 0.3% of Nd, and the balance of Ti and unavoidable impurity elements.
  3. 3. The preparation method of the rare earth modified casting high-temperature titanium alloy is characterized by comprising the following steps of: S1, raw material smelting, namely weighing the raw materials according to the component proportion of any one of claims 1-2, and carrying out vacuum arc smelting and repeated ingot turning remelting to obtain alloy ingots with uniform components; S2, performing structure-regulated hot isostatic pressing treatment, namely placing the alloy cast ingot into hot isostatic pressing equipment, and continuously performing the following five stages of treatment under a protective atmosphere: (1) The first stage, namely preserving heat for 0.3-0.6 hour under the conditions that the temperature is 900-920 ℃ and the pressure is 220-250 MPa; (2) The second stage, namely raising the temperature to 970-990 ℃ and adjusting the pressure to 80-100 MPa, and preserving the heat for 1.0-1.8 hours; (3) The third stage, namely reducing the temperature to 940-960 ℃, and then controlling the pressure according to the following sequence: (a) Firstly, the pressure is raised to 170-180 MPa, and the pressure is kept for 0.15-0.3 hour; (b) Then the pressure is reduced to 130-140 MPa, and the pressure is kept for 0.15-0.3 hours; (c) Raising the pressure to 150-160 MPa again, and keeping for 0.2-0.4 hours; (4) The fourth stage, namely reducing the temperature to 910-930 ℃, increasing the pressure to 190-210 MPa, and preserving the heat for 1.5-2.2 hours; (5) A fifth stage of cooling the temperature from the ending temperature of the fourth stage to 850 ℃ at a rate of not more than 5 ℃ per minute in the process of linearly reducing the pressure from 190-210 MPa to 100 MPa; And S3, finally cooling, namely cooling the alloy from 850 ℃ to room temperature.
  4. 4. A method according to claim 3, wherein step S1 comprises: S11, raw materials are weighed and prepared, namely Ti, al, zr, sn, mo, si, nb, ta, W and Nd raw materials are respectively weighed, wherein rare earth Nd blocks are independently sealed and stored; S12, charging and vacuum preparation, namely uniformly mixing all raw materials except Nd blocks, placing the raw materials and the Nd blocks wrapped by titanium foil into a water-cooled copper crucible of a vacuum arc melting furnace, wherein the Nd blocks are placed in the middle of the mixed raw materials; s13, smelting and stirring, namely smelting under the protection of argon, controlling the smelting current to be 600-800A, heating to 2200-2500 ℃, smelting for 2-3 min each time, and applying electromagnetic stirring for 30-40S in an alloy molten state; S14, turning over the ingot for remelting and cooling the ingot, namely turning over the ingot for 180 degrees after one-time smelting, repeating the smelting operation of the step S13, turning over the ingot for 4-6 times, cooling the ingot for 2-3 min between two adjacent times, naturally cooling the ingot to below 200 ℃ under the protection of argon after the last smelting, cooling for 20-30 min, and then taking out the cast alloy ingot.
  5. 5. A method according to claim 3, wherein in step S3 the cooling rate is not more than 30 ℃ per minute at a temperature above 500 ℃.
  6. 6. Use of a rare earth modified cast high temperature titanium alloy according to any one of claims 1 to 2 or a rare earth modified cast high temperature titanium alloy produced by the production method according to any one of claims 3 to 5 for producing structural members of aeroengines or gas turbines in service for long periods of time at temperatures of 650 ℃ and above.

Description

Rare earth modified casting high-temperature titanium alloy and preparation method and application thereof Technical Field The invention relates to the technical field of high-temperature titanium alloy materials, in particular to a rare earth modified cast high-temperature titanium alloy, a preparation method and application thereof. Background The high-temperature titanium alloy has become the first choice material of the key hot end components of high-end equipment such as aerospace engines, gas turbines and the like by virtue of the excellent specific strength, the good high-temperature mechanical property and corrosion resistance. The near alpha-type titanium alloy is widely researched, developed and applied at home and abroad due to good high-temperature strength and thermal stability, such as Ti-1100 in the United states, IMI834 in the United kingdom, and brands of Ti60, ti600 and the like in China. However, with the rapid development of aerospace technology, the requirements on thrust-weight ratio and efficiency of engines are continuously increased, so that service temperatures born by key components are increasingly increased. Currently, the long-term stable service temperature of conventional high temperature titanium alloys is generally limited to around 600 ℃. When the service temperature is close to or exceeds 650 ℃, the existing alloy faces two serious challenges, namely, firstly, the titanium alloy is easy to form a loose oxide layer at high temperature, and meanwhile, oxygen atoms can diffuse into a matrix to form a brittle oxygen-enriched alpha layer, so that the plasticity, fatigue performance and long-term service life of the material are seriously damaged. Secondly, it is also a more central limiting factor, namely tissue destabilization at high temperatures. In a near- α titanium alloy based on a Ti-Al-Sn-Zr system, it is generally necessary to add a relatively high content of Al element in order to obtain high-temperature strength. However, during long-term exposure (thermal exposure) at 650 ℃ and above, al, sn, and other elements in the bulk tend to be ordered within the α phase, precipitating a Ti 3 Al ordered phase (also referred to as the α 2 phase) having a close-packed hexagonal (D0 19) structure. The phase is a hard and brittle phase, and a large amount of precipitation and coarsening of the phase can seriously fracture a matrix, so that the plasticity, toughness and creep property of the alloy are obviously reduced, namely the phenomenon of thermal exposure embrittlement occurs. This is a fundamental scientific problem that limits the use temperature window of high temperature titanium alloys to break through the 650 ℃ bottleneck. To overcome this problem, researchers have tried various methods. Alloying is an important approach, for example, adding Nb, ta, mo, W or other beta-stabilizing elements to increase high temperature strength and thermal stability, and adding Si to improve creep properties. However, the addition of these elements may adversely affect other properties (e.g., plasticity, casting fluidity) while improving one property, and has limited effect of suppressing precipitation of the ordered phases of Ti 3 Al. Another idea is to refine the structure using a thermo-mechanical treatment, but this is often difficult to implement for cast components of complex shape. Therefore, the novel casting high-temperature titanium alloy is developed, so that the novel casting high-temperature titanium alloy has good casting manufacturability, can keep excellent tissue stability and mechanical property in the long-term service process at the temperature of 650 ℃ and above, and can inhibit the precipitation of a Ti 3 Al brittle phase, so that the novel casting high-temperature titanium alloy becomes a key technical problem to be solved in the field. Disclosure of Invention Aiming at the technical bottlenecks of tissue instability and performance embrittlement caused by the precipitation of ordered phases of Ti 3 Al when the existing high-temperature titanium alloy is in service at the temperature of 650 ℃ and above for a long time, the invention provides a rare earth modified casting high-temperature titanium alloy and a preparation method and application thereof. The invention aims to effectively inhibit precipitation and growth of a brittle ordered phase while realizing tissue purification through unique alloy component design and an innovative multi-stage hot isostatic pressing process, so as to obtain the cast high-temperature titanium alloy material with excellent high-temperature strength, good plasticity and excellent long-term tissue stability. In order to achieve the above purpose, the invention adopts the following specific scheme: In a first aspect, the invention provides a rare earth modified cast high-temperature titanium alloy, which comprises the following components ：Al 5.50%～6.50%,Sn 3.50%～5.00%,Zr 3.50%～5.00%,Mo 0.20%～0.80%,Si 0.10%～0.30%,Nb 0.25%～0.55%,Ta 0.