RU2237093C1 - INTERMETALLIC Ni3Al -BASED ALLOY AND PRODUCT MADE FROM THE SAME - Google Patents

Abstract

FIELD: metallurgy, in particular casting fire-resistant alloys.

SUBSTANCE: invention relates to casting fire-resistant intermetallic Ni₃Al-based alloy and products, manufactured by precision casting (e.g. moving blades, nozzle blades, combustion chamber constructional elements, leafs and other parts of gas-turbine engines) used in aerotechnics, automobile industry, shipbuilding, as well as to product therefrom. Claimed alloy contains (mass.%) aluminum 8.5-9.5; chromium 4.8-5.5; molybdenum 2.5-3.5; tungsten 2.6-3.2; titanium 1.0-1.6; carbon 0.001-0.005; additionally rhenium 1.5-3.5 and lanthanum 0.0015-0.015; and balance: nickel and inevitable impurities. Products made from disclosed alloy exhibit improved margin of safety and endurance due to increased short-time strength at room temperature, fire-resistance at 1100⁰C (based on100 h-testing), heat resistance at 1250⁰C and fatigue strength at room temperature.

EFFECT: improved casting allow and product made from the same.

2 cl, 2 tbl, 1 ex

Description

The invention relates to the field of metallurgy, in particular to heat-resistant foundry alloys based on intermetallic Ni ₃ Al and products obtained by precision casting, such as, for example, working and nozzle blades, elements of combustion chambers, sashes and other parts of gas turbine engines used in aircraft , automotive industry, shipbuilding.

Known alloy based on intermetallic Ni ₃ Al composition, wt.%:

Al 8.0-9.5

Fe 4.0-6.0

Mo 0.5-1.5

Hf 0.5-1.0

From 4.0-5.0

B 0.02 - 0.04

C 0.03-0.06

Ni Else

U.S. Patent No. 5108700

The disadvantage of this alloy is unsatisfactory strength at temperatures of 1100 and 1200 ° C and low ductility at room temperature.

Products from this alloy are used, for example, for gas pumping installations at operating temperatures up to 900 ° C.

Known alloy based on intermetallic Ni ₃ Al, having a composition, wt.%:

Al 8.0-9.0

Cr 5.0-6.8

Mo 3.0-4.3

W 2.7-4.0

Ti 1.3-2.2

S 0.13-0.18

Sn 0.03-0.08

Ni Else

RF patent No. 2088686

The disadvantage of this alloy is unsatisfactory heat resistance in the temperature range 900-1100 ° C at the test bases of 100 and 500 hours and insufficiently high heat resistance at a temperature of 1200 ° C.

The disadvantage of products, such as dies for isothermal stamping, is the insufficient level of operating temperatures and short service life.

The closest analogue, taken as a prototype, is an alloy based on intermetallic Ni ₃ Al, having a composition, wt.%:

Al 7.8-9.0

Cr 5.0-6.5

Mo 3.0-4.0

W 2.7-4.0

Ti 0.8-1.2

C 0.001-0.005

Sn 0.03-0.05

Zr 0.05-0.5

Ni Else

RF patent No. 2198233

The disadvantage of this alloy is unsatisfactory short-term strength at room temperature, insufficient heat resistance at a temperature of 1100 ° C based on a test of 100 hours, insufficient heat resistance at a temperature of 1250 ° C and endurance limit at room temperature.

The alloy can be used both for non-force structures, for example nozzle blades, valves of an adjustable nozzle, and for power rotor blades of a gas turbine engine. Products from this alloy have a limited service life.

The technical task of the invention is the creation of an alloy based on intermetallic Ni ₃ Al and products from this alloy with increased short-term strength at room temperature, heat resistance at a temperature of 1100 ° C based on a test of 100 hours, heat resistance at a temperature of 1250 ° C and endurance at room temperature temperature.

To achieve the technical task, an alloy based on intermetallic Ni ₃ Al is proposed, containing aluminum, chromium, molybdenum, tungsten, titanium, carbon, which additionally contains rhenium and lanthanum, in the following ratio, wt.%:

Al 8.5-9.5

Cr 4.8-5.5

Mo 2.5-3.5

W 2.6-3.2

Ti 1.0-1.6

C 0.001-0.005

Re 1.0-3.5

La 0.0015-0.015

Ni Else

and an article made from it.

The proposed alloy will find application both for non-force structures: nozzle vanes, parts of combustion chambers, and for power: turbine engine blades.

The authors found that, with the stated ratios of the components in the proposed alloy based on Ni ₃ A1, the introduction of rhenium, which increases the temperatures of solidus (T _s ) and liquidus (T _L ), dissolves in a γ-solid solution (solution based on nickel), strengthening it and lanthanum, which forms the Ni ₃ Al (La) intermetallic compound located at the phase boundaries, provides the greatest effect of increasing the short-term strength of the alloy based on the NiaAl intermetallic compound at room temperature, heat resistance at a temperature of 1100 ° С based on a test of 100 hours and growth resistance at a temperature of 1250 ° C and fatigue limit at room temperature on single-crystal samples.

Examples of implementation.

The charge stock from the proposed alloy of various compositions and the prototype alloy was smelted from pure charge materials in a vacuum induction furnace with a crucible from the main lining. After casting the alloys in a mold ⌀ 60 mm, chips were taken for chemical analysis. The chemical composition of the proposed alloy and the alloy of the prototype are shown in table 1.

Before subsequent operations, the billet was machined along the surface to a depth of 1-2 mm to remove the layer in contact with cast iron, then cut into measured billets weighing 2 kg for subsequent remelting. After remelting, samples ⌀ 16 mm and a length of 150 mm were obtained.

Machined samples and parts were heat treated in air according to the following regime: annealing at a temperature of 1150 ± 10 ° С for 1 h, cooling in air.

The properties of the proposed alloy and the prototype alloy are shown in table 2, was determined on standard samples at a ratio of 1 / d = 5.

From table 2 it is seen that the properties of the proposed alloy based on intermetallic Ni ₃ Al higher than the properties of the known alloy of the prototype:

short-term strength at room temperature (σ $\genfrac{}{}{0ex}{}{\text{20}}{\text{in}}$ ) - by 15.7-19.8%, heat resistance at a temperature of 1100 ° С based on a test of 100 hours (σ $\genfrac{}{}{0ex}{}{\text{1100}}{\text{100}}$ ) - by 23.8-33.3%, heat resistance at a temperature of 1250 ° С (by weight gain during oxidation in 100 hours) - by 16-28%, the endurance limit at room temperature (σ $\genfrac{}{}{0ex}{}{\text{20}}{\text{-1}}$ ) on the basis of 2 × 10 ⁷ - by 54.2-58.3%.

The use of the proposed alloy based on intermetallic Ni ₃ Al increases the reliability of products, for example, working and nozzle blades, elements of combustion chambers, shutters of an adjustable nozzle and other parts of gas turbine engines used in aircraft, as well as in transport engineering, and increases the resource of their work.

Claims (2)

1. An alloy based on intermetallic Ni ₃ Al containing aluminum, chromium, molybdenum, tungsten, titanium, carbon, characterized in that it additionally contains rhenium and lanthanum in the following ratio, wt.%: Al 8.5-9.5 Cr 4.8-5.5 Mo 2.5-3.5 W 2.6-3.2 Ti 1.0 -1.6 C 0.001-0.005 Re 1.0-3.5 La 0.0015-0.015 Ni Else 2. An alloy product based on intermetallic Ni ₃ Al, characterized in that it is made of an alloy according to claim 1.