RU2349663C1 - ALLOY ON BASIS OF INTERMETALLIC COMPOUND Ni3Al AND PRODUCT, MADE OF IT - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention concerns metallurgy field. Particularly it concerns castable alloy on the basis of intermetallic compound Ni₃Al and products, received by means of investment casting method with directed columnar and monocrystalline structures, such as buckets and nozzle blades, nozzle blades blocks and other details of gas turbine engines for aircraft, automotive industry. For increasing of high-temperature strength of alloy in the range of temperatures 900-1100°C on the basis of 500 hours and increasing of ingot yield at moulding of details with monocrystalline structure from alloy it contains, wt %: Al 8.0-9.0, Cr 4.5-5.5, W 1.8-2.5, Mo 4.5-5.5, Ti 0.6-1.2, C 0.01-0.08, Co 3.5-4.5, La 0.0015-0.015, Sc 0.015-0.03, Ni - the rest.

EFFECT: increasing of high-temperature strength and product yield.

2 cl, 2 tbl, 1 ex

Description

The invention relates to the field of metallurgy, in particular to cast alloys based on Ni ₃ Al intermetallic and products obtained by precision casting on investment casting with directional columnar and single-crystal structures, such as, for example, working and nozzle blades, nozzle blade blocks and other details gas turbine engines of the aviation, automotive industry.

Known alloy based on intermetallic Ni ₃ Al of the following chemical composition, wt.%:

Al 7.6-8.5 Mo 6.1-9.6 Cr 3.8-7.7 Zr 0.07-0.34 AT 0.01-0.33 Ni rest

(US patent No. 6106640).

The disadvantage of this alloy is zero ductility at room temperature and poor ductility in the temperature range 100-800 ° C.

Products from this alloy are used for ground-based gas turbine engines at operating temperatures up to 1100 ° С.

Known alloy based on intermetallic Ni ₃ Al and products obtained by the methods of granular metallurgy, the following chemical composition, wt.%:

Al 8.0-9.0 Cr 4.0-5.0 W 4,5-5,5 Mo 1.8-3.2 Ti 1.2-2.0 That 1.2-2.2 FROM 0.03-0.09 Er 0.02-0.08 Ni rest

(RF patent No. 2297467).

The disadvantage of this alloy is poor endurance at temperatures of 20 and 900 ° C.

From this alloy parts with a small resource are made.

Known alloy based on intermetallic Ni ₃ Al of the following chemical composition, wt.%:

Al 7.7-8.7 Cr 5.0-6.0 W 2.5-3.5 Mo 4,5-5,5 Ti 0.3-0.8 FROM 0.001-0.02 With 4.0-6.0 Re 1.2-1.8 La 0.002-0.2 Zr 0.05-0.5 Ni rest

(RF patent No. 2256716).

The disadvantage of this alloy is the increased density and unsatisfactory heat resistance at a temperature of 1200 ° C for 100 hours, which limits the range of cast products.

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

Al 8.0-9.0 Cr 4,5-5,5 W 1.8-2.5 Mo 4,5-5,5 Ti 0.6-1.2 FROM 0.12-0.2 With 3.5-4.5 La 0.0015-0.015 Zr 0.05-0.5 Ni rest

and a product made from it (RF patent No. 225387).

The disadvantage of this alloy is poor heat resistance in the temperature range 900-1100 ° C based on a test of 500 hours.

The disadvantage of products made from this alloy is the low yield when casting parts with directional columnar and single-crystal structures.

The technical task of the invention is to increase the heat resistance of an alloy based on intermetallic Ni ₃ Al in the temperature range 900-1100 ° C for 500 hours and to increase the yield when casting parts with directional columnar and single-crystal structures.

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

Al 8.0-9.0 Cr 4,5-5,5 W 1.8-2.5 Mo 4,5-5,5 Ti 0.6-1.2 FROM 0.01-0.08 With 3.5-4.5 La 0.0015-0.015 Sc 0.015-0.03 Ni rest

and an article made from it.

The alloy may contain sulfur, phosphorus, iron, silicon, lead, bismuth, tin and antimony as impurities, respectively, in amounts less than or equal to, wt.%: 0.005; 0.015; 0.5; 0.4; 0.001; 0,0005; 0.003; 0.003.

The authors found that when scandium, which acts as a deoxidizer, is introduced into the composition and the content and ratios of the components are proposed in the proposed alloy based on the Ni ₃ Al intermetallic alloy, a decrease in the oxygen content in the melt and the formation of a finely dispersed intermetallic phase are observed, with the greatest effect of increasing the heat resistance of the alloy in the temperature range 900-1100 ° С and increase in yield when casting products with directional columnar and single-crystal structures.

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 molds ⌀ 90 mm, chips were taken for chemical analysis. The results of chemical analysis of the alloy compositions are shown in table 1.

The content of alloying elements, gases and impurities, such as sulfur, phosphorus, antimony, bismuth was determined by standard methods.

Before subsequent operations, the billet was poured over 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.

Blanks for samples ⌀ 16 mm and a length of 150 mm were obtained by directional crystallization in vacuum.

The surface of the samples and parts was controlled by detecting the macrostructure by etching in a mixture of hydrochloric acid and hydrogen peroxide. In the presence of one macro-grain along the axis of the sample, castings are considered to be single-crystal, in the presence of two or more grains without pinching out, with a directed columnar structure.

In order to increase the heat resistance of the alloy at high temperatures, as well as the stability of properties, 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 with a different ratio of components and the prototype alloy obtained by the same technological scheme are shown in table 2.

From table 2 it is seen that the properties of the proposed alloy based on intermetallic Ni ₃ Al are higher than the properties of the known prototype alloy: heat resistance at a temperature of 900 ° C based on a test of 500 hours on samples with directional columnar structure (σ ⁹⁰⁰ ₅₀₀ ) - by 27, 6 - 37.9%, with a single crystal structure - 66.7 - 72.7%; heat resistance at a temperature of 1000 ° C based on a test of 500 hours with a directional columnar structure (σ ¹⁰⁰⁰ ₅₀₀ ) - by 66.7 - 111.1%, with a single-crystal structure - by 36.8 - 57.9%; heat resistance at a temperature of 1100 ° C based on a test of 500 hours with a directional columnar structure (σ ¹¹⁰⁰ ₅₀₀ ) - by 57.1 - 100%, with a single crystal structure - by 77.8 - 100%; yield of parts with directional columnar structure - by 27.8 - 31.9%, with a single-crystal structure - by 1.5-1.75 times.

The use of the proposed alloy based on intermetallic Ni ₃ Al increases the reliability of parts and increases the resource of their work.

Claims (2)

1. An alloy based on intermetallic Ni ₃ Al containing aluminum, chromium, tungsten, molybdenum, titanium, carbon, cobalt, lanthanum, nickel, characterized in that it additionally contains scandium in the following ratio of components, wt.%:
Al 8.0-9.0 Cr 4,5-5,5 W 1.8-2.5 Mo 4,5-5,5 Ti 0.6-1.2 FROM 0.01-0.08 Co 3.5-4.5 La 0.0015-0.015 Sc 0.015-0.03 Ni rest 2. An alloy product based on intermetallic Ni ₃ Al, characterized in that it is made of an alloy according to claim 1.