High-strength high-ductility TiAl alloy material and preparation method thereof

An alloy material and high plasticity technology, applied in the field of intermetallic compound materials, can solve problems such as affecting the room temperature performance of TiAl alloys, achieve universal applicability and promotion value, improve room temperature brittleness, and prevent alloy pollution.

Active Publication Date: 2015-01-14
NANJING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, since the Nb element is an element with a strong ability to stabilize the β phase, it is easy to form a large amount of β segregation at a relatively slow growth rate during the direction...

Method used

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  • High-strength high-ductility TiAl alloy material and preparation method thereof
  • High-strength high-ductility TiAl alloy material and preparation method thereof
  • High-strength high-ductility TiAl alloy material and preparation method thereof

Examples

Experimental program
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Embodiment 1

[0033] (1) Selection of raw materials:

[0034] The alloy composition selected for preparing the master alloy ingot in the present invention is Ti47Al45Nb8 (atomic percentage), and the purity of each metal component is 99.999% for Ti and Al, and 99.95% for Nb.

[0035] (2) Preparation of master alloy ingot:

[0036] Under the protection of high-purity argon gas, master alloy ingots are melted in a water-cooled copper crucible electromagnetic induction suspension melting furnace: after the surface of the metal raw material is mechanically polished to remove the surface oxide skin, the material is prepared according to the designed composition ratio; according to each ingot Put the prepared material into the water-cooled copper crucible in the melting furnace with a weight of about 70g, and vacuumize to 5×10 -3 Pa; fill a certain amount of high-purity argon gas (99.999%) into the furnace, and the pressure range of argon gas is 0.8-1MPa. Multi-pass smelting for 3 to 4 times to ...

Embodiment 2

[0044] Using the same preparation method as in Example 1, the alloy composition is Ti44Al47Nb9 (atomic percentage), the optical floating zone directional solidification process is a relative rotational speed of 20rpm, a heating power of 55%, a growth rate of 2.5mm / h, and a vacuum heat treatment process of 1250°C× 12h+900℃×30min / furnace cooling, the B2 phase is completely eliminated, and the obtained TiAl alloy material has a tensile yield strength of 550MPa at room temperature and a plastic strain of 6.0%.

Embodiment 3

[0046] Using the same preparation method as in Example 1, the alloy composition is Ti51Al40Nb9 (atomic percentage), the optical floating zone directional solidification process is a relative rotational speed of 25 rpm, the heating power is 70%, the growth rate is 10 mm / h, and the vacuum heat treatment process is 1300 ° C × 20 h +900°C×30min / furnace cooling, the B2 phase is completely eliminated, and the obtained TiAl alloy material has a tensile yield strength of 628MPa at room temperature and a plastic strain of 6.5%.

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Abstract

The invention discloses a high-strength high-ductility TiAl alloy material and a preparation method thereof. The high-strength high-ductility TiAl alloy material comprises Ti, Al and Nb, wherein the atomic percent is (44-51)Ti-(43-47)Al-(6-9)Nb. The preparation method of the high-strength high-ductility TiAl alloy material comprises the following steps of carrying out electromagnetic induction suspension smelting on a TiAl alloy mother alloy ingot by adopting a water-cooled copper crucible, and carrying out suction casting to obtain a mother alloy rod; carrying out directional solidification on the mother alloy rod by adopting a four-mirror optical floating region directional solidification furnace, controlling the orientation of a TiAl alloy lamella, and acquiring a PST crystal; carrying out heat treatment and stress relief annealing on the PST crystal in an alpha single-phase region through a vacuum heat treatment furnace, and removing B2-phase segregation and residual stress to finally form the high-strength high-ductility TiAl alloy material. The high-strength high-ductility TiAl alloy material prepared through the method disclosed by the invention prevents the pollution of the water-cooled copper crucible on a TiAl alloy in a melting process, overcomes the defects of nonuniform component property and complicated processing of the traditional seed crystal method, is enhanced in strength and obtains outstanding room temperature tensile ductility.

Description

technical field [0001] The invention belongs to the technical field of intermetallic compound materials, and specifically prepares a TiAl alloy material with high strength and high plasticity at room temperature by adopting an optical floating zone directional solidification method and vacuum heat treatment on the basis of rationally designing alloy components. Background technique [0002] TiAl intermetallic compound has low density, high elastic modulus and good high temperature strength, creep resistance and oxidation resistance. Its service temperature can reach 750-900°C, which is similar to that of Ni-based superalloys; but its density is only half that of superalloys, so it is an ideal substitute material for Ni-based superalloys, and can be widely used in high-temperature parts of automobiles or aero-engines Such as blades, turbine discs and exhaust valves. [0003] However, due to the intrinsic brittleness of intermetallic compounds, the poor room temperature britt...

Claims

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Application Information

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IPC IPC(8): C22C14/00C22C1/03C22F1/18C30B21/04C30B29/52
Inventor 陈光彭英博李沛郑功祁志祥苏翔王敏智
Owner NANJING UNIV OF SCI & TECH
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