RU2586947C1 - Titanium-based alloy and article made therefrom - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to intermetallic titanium-based alloys intended for production of parts of gas turbine engine such as blades, discs, housing and spacers, operating at high temperatures. Ti based alloy contains in % by weight: Al 9.5-12.0, Nb 38.0-42.0, Zr 1.5-2.5, Ta 0.7-1.5, W 0.5-1.0, Mo 0.3-0.6, Si 0.1-0.25, Re 0.1-0.5, C 0.03-0.08, B 0.01-0.1, Ti and admixtures are rest. Alloy is characterised by high resistance to oxidation at temperatures higher than 700 °C.

EFFECT: reliable operation of structure made using titanium-based alloy for whole service life.

6 cl, 2 tbl, 4 ex

Description

The invention relates to the field of non-ferrous metallurgy, in particular to titanium-based intermetallic alloys intended for the manufacture of gas turbine engine parts such as blades, disks, housings and spacers operating at elevated temperatures.

Known intermetallic alloy based on titanium (EP 0924308 A1, 06.23.1999, C22C 14/00), having the following chemical composition, wt.%:

Al 16-26 Nb 18-28 That 0-2 Mo 0-2 Zr 0-2 Si 0-0.8 Ti rest

The alloy has low values of specific strength at room temperature and specific heat resistance (short-term and long-term strength for 100 hours) due to the increased density. Structural elements made of a known alloy have increased oxidation, which leads to a limited life of the part.

Known intermetallic alloy based on titanium (RU 2210612 C2, 08/20/2003, C22C 14/00), having the following chemical composition, wt.%:

Al 10.0-12.0 Nb 38.0-42.0 V 1.0-1.5 Mo 0.5-1.0 Zr 1.0-1.5 Si 0.1-0.25 FROM 0.03-0.08 Ti rest

The alloy has not enough high values of specific heat resistance - short-term and long-term strength for 100 h, creep resistance, and also has a low resistance to oxidation in air at temperatures above 650 ° C.

The closest analogue taken as a prototype is an intermetallic alloy based on titanium (RU 2405849 C1, 12/10/2010, C22C 14/00), having the following chemical composition, wt.%:

Al 10.5-12.5 Nb 38.0-42.0 V 1.0-1.5 Mo 0.3-0.6 Zr 1.5-2.5 Si 0.1-0.25 FROM 0.03-0.08 W 0.5-1.0 Ta 0.7-1.5 Ti rest

The alloy has good values of specific heat resistance (short-term and long-term strength for 100 h), but reduced characteristics of heat resistance at temperatures above 700 ° C.

An object of the invention is the development of an intermetallic alloy based on titanium with improved heat resistance characteristics.

The technical result is increased resistance to oxidation at temperatures above 700 ° C.

To achieve the technical result, an alloy based on titanium containing aluminum, niobium, zirconium, tantalum, tungsten, molybdenum, silicon, carbon, characterized in that it additionally contains rhenium and boron in the following ratio of components, wt.%:

Al 9.5-12.0 Nb 38.0-42.0 Zr 1.5-2.5 That 0.7-1.5 W 0.5-1.0 Mo 0.3-0.6 Si 0.1-0.25 Re 0.1-0.5 FROM 0.03-0.08 AT 0.01-0.1 Ti and impurities rest

Preferably, the copper content is ≤0.07.

Preferably, the iron content is ≤0.03.

Preferably, the chromium content is ≤0.02.

Preferably, the sum of the impurities is ≤0.12.

Products from the proposed alloy are able to work for a long time in air at temperatures up to 750 ° C.

The authors found that a decrease in the aluminum content, the exclusion of vanadium from the alloys and the additional introduction of rhenium and boron into the prototype alloy, with the stated ratio and content of components, increase the heat resistance characteristics of the alloys. This is due to the following factors:

- the formation on the surface of the alloy of layers of mixed oxides Ti ₃ O ₅ , (Ti, Al, B) O ₃ and (Nb, Ta) ₂ O ₅ blocking the penetration of oxygen to the gas-metal interface;

- preservation to a temperature of 750 ° C of ordered solid titanium solutions with elements - Nb, Mo, W, Ta and Re, which reduce the diffusion coefficients of oxygen in the matrix, making it difficult to form oxide phases.

To obtain improved heat resistance characteristics, it is necessary to limit the content of elements - Cu, Fe, and Cr, which accelerate the diffusion of oxygen at the interphase boundaries in the alloy structure, reduce the temperature boundary of the existence of ordered solid solutions, thereby causing the formation of porous oxide layers and increased oxidation of the alloys.

Examples of implementation

The ingots of the proposed alloys were made according to the production technology of titanium alloys. Serial charge materials were used - titanium sponge, Al-Me ligatures, where Me - refractory alloying elements, boron and silicon. The manufacture of alloy ingots consisted of producing a consumable electrode, smelting the ingots by vacuum-arc remelting, and machining the ingots. Cast billets were subjected to hot pressure treatment in order to obtain semi-finished products with a uniform structure. Semi-finished products were cut into sample blanks and subjected to heat treatment to obtain the optimal phase composition and structure. Test samples were made from the obtained blanks. Finished samples had a surface finish of at least R _z = 3.2.

Heat resistance tests were carried out in accordance with GOST 6130-71 using cylindrical samples with a diameter of 15 mm and a height of 20 mm. The samples were heated in electric resistance furnaces in an air atmosphere with a humidity of 55-60%. The heat resistance of the alloys was evaluated by the weight gain of the samples Δm / s (g / m ² ) at temperatures of 700 and 750 ° C and a holding time of 100 hours with periodic weighing of the tested samples every 25 hours.

The compositions of the proposed alloy No. 1-3 and alloy prototype No. 4 are shown in table 1.

Table 2 shows the heat resistance characteristics of the proposed alloys No. 1-3 and prototype alloy No. 4.

As can be seen from table 2, the proposed alloy exceeds the prototype alloy in heat resistance at a temperature of 700 ° C by 14.7% and at a temperature of 750 ° C by 36.0%.

Using the proposed alloy as a heat-resistant material will ensure reliable operation of the structure throughout the life of the resource.

Claims (6)

1. An alloy based on titanium containing aluminum, niobium, zirconium, tantalum, tungsten, molybdenum, silicon and carbon, characterized in that it additionally contains rhenium and boron in the following ratio of components, wt.%:
Al 9.5-12.0 Nb 38.0-42.0 Zr 1.5-2.5 That 0.7-1.5 W 0.5-1.0 Mo 0.3-0.6 Si 0.1-0.25 Re 0.1-0.5 FROM 0.03-0.08 AT 0.01-0.1 Ti and impurities rest 2. The alloy according to claim 1, characterized in that it additionally contains copper ≤0.07 wt.%. 3. The alloy according to claim 1, characterized in that it additionally contains iron ≤0.03 wt.%. 4. The alloy according to claim 1, characterized in that it additionally contains chromium ≤0.02 wt.%. 5. The alloy according to claim 1, characterized in that the total content of impurities is ≤0.12 wt.%. 6. A product of an alloy based on titanium, characterized in that it is made of an alloy according to claim 1.