DE102014108462A1 - Heat-resistant conductive aluminum-based alloy (options) and a process for making deformed semi-finished products thereof - Google Patents

Abstract

The invention relates to metallurgy, in particular deformable aluminum, copper and manganese-based nanostructure alloys, and to a method for obtaining them for products working at high temperatures. An aluminum-based alloy contains components in the following ratio,% by weight: copper 0.5-0.85; Manganese 0.5-0.95; Boron 0.02-0.15; Zircon 0.1-0.5; Scandium 0.02-0.15; Iron 0.01-0.3; Silicon 0.01-0.15, unavoidable foreign substances 0-0.1, each of them 0-0.03, aluminum residue. Boron is present in the structure in the form of nanoparticles of AlB2, AlB12, borides (including those with unavoidable foreign substances) to ensure a conductivity higher than 54% IACS and a strength limit (σϐ) after 400 hours of heating at 250 ºС not less than 160 MPa , To increase the strength limit after 400 hours when heated at 250 ºС to 230-280 MPa, the alloy differs in the following component ratio,% by weight: copper 0.9-2.0; Manganese 1.0-1.6; Boron 0.02-0.15; Zircon 0.1-0.5; Scandium 0.02-0.15; Iron 0.01-0.3; Silicon 0.01-0.15, unavoidable foreign substances 0-0.1, each of them 0-0.003, residual aluminum. Boron forms a permanent segregation in areas close to the border due to crystal defects, which increases the deformability of the alloy and changes the aging kinetics.

Description

The invention relates to metallurgy, in particular deformable nanostructured alloys based on aluminum, copper and manganese, and the process for their recovery for use in the high-temperature products. In particular, the alloy may be used in aerospace, aerospace, automotive, electrical engineering products where the combination of sufficient and differential strength, conductivity and heat resistance is required.

Al-Cu-Mn-based alloys with a high copper content are known (US Pat. " Mechanical engineering. Encyclopedia in 40 volumes »Volume II-3. Non-ferrous metals and alloys. Moscow, Publisher Maschinostrojenie, 2001, pp. 144-156 ). These are the alloys D20, 1201, D21, 01205 with a copper content of 5.8-7.0% of the mass (wt.%). They have a conductivity that does not exceed 30-35% IACS, which is due to their use after curing and artificial aging and high copper content.

According to patent ( Patent of the Russian Federation No. 2287600 , IPC С22С21 / 12, published. on November 20, 2006), a copper, manganese, zirconium and vanadium-containing alloy is known, which contains aluminum solid solution and secondary aluminides, characterized in that it additionally contains scandium with the following component ratio, wt.%: Copper 1 , 2-2.4; Manganese 1.2-2.2; Zirconium 0.5-0.6; Vanadium 0.01-0.15; Scandium 0.01-0.2; Aluminum residue. After 100 hours of holding, the alloy has a strength limit of over 30 MPa at 350 º C. At a high strength limit after annealing for 1-20 min. Below 200-410 ° C, which is 300 MPa, the alloy has a low conductivity of less than 48% IACS.

The closest to the object according to the application is the aluminum-based alloy (patent of Russian Federation No. 2446222 , IPC С22С21 / 14, С22F1 / 057, published. on 27.03.2012), the components in the following ratio, wt.%: Copper 0.9-1.9; Manganese 1.0-1.8; Zirconium 0.2-0.64; Scandium 0.01-0.12; Iron 0.15-0.5; Silicon 0.05-0.15; Aluminum residual, nanoparticles of phase Al3 (Zr, Sc) with an average size of less than 20 nm, the conductivity exceeds 53% IACS, the limit strength (σ _β ) after 100 hours at 300 ºС exceeds 320 MPa.

Disadvantageous of this alloy, in spite of numerous advantages, is the insufficient holding strength of 400 hours (250 ° C.) and the conductivity of less than 53% IACS.

The object of the invention is to develop a novel nano-structural deformable aluminum-based alloy which has higher heat resistance and conductivity.

The object is achieved in that a heat-resistant conductive aluminum-based alloy containing copper, manganese, zirconium, scandium, iron and silicon, aluminum solid solution and secondary manganese, zirconium and scandium aluminides, characterized in that they additionally boron with following component ratio, wt.%:
Copper 0.5-0.85
Manganese 0.5-0.95
Boron 0.02-0.15
Zircon 0.1-0.5
Scandium 0.02-0.15
Iron 0.01-0.30
Silicon 0.01-0.15
inevitable foreign matter 0-0.1, each 0-0,003
Aluminum residue.

Here, boron is present in the structure in the form of nanoparticles of AlB ₂ , AlB ₁₂ , borides (including inevitable impurities) with average size less than 50 nm to provide conductivity greater than 54% IACS and a toughness limit of 400 hours at 250 ºС not less than 160 MPa.

The object is also achieved by containing a heat-resistant conductive aluminum-based alloy, copper, manganese, zirconium, scandium, iron and silicon, aluminum solid solution and secondary manganese, zirconium and scandium aluminides, characterized in that they additionally contain boron having the following component ratio, wt.%:
Copper 0.9-2.0
Manganese 1.0-1.6
Boron 0.02-0.15
Zircon 0.1-0.5
Scandium 0.02-0.15
Iron 0.01-0.30
Silicon 0.01-0.15
inevitable foreign matter 0-0.1, each 0-0,003
Aluminum residue.

To increase the strength limit after 400 hours at 250 ºС up to 230-280 MPa.

In this case, boron forms a constant segregation in border areas on crystal defects, whereby the deformability of the alloy is increased and the aging kinetics is changed. For a more stable increase in heat resistance, the alloy may additionally contain: wt%, cobalt 0.1-0.45 and / or nickel 0.1-0.35, and / or cadmium 0.1-0.3.

The alloy may be manufactured in the form of various deformed semi-finished products, the manufacturing process of which includes melt preparation at a temperature exceeding the liquidus temperature of 100 ° C., introduction of components into the melt in the form of additional alloys having a fine crystalline structure and an average size of Nanoparticles up to 1500 nm, with the use of additional alloys Al-B-Ti or Al-Cu-Mn (Ti), the titanium content in the melt is limited to 0.05 wt.%.

In addition, the crystallization of the cast semi-finished product and its deformation under the action of a pulse magnetic field and / or weak pulse current is carried out in order to ensure the required size of nanoparticles and the heat resistance.

Manganese, zirconium and cobalt inhibit the decomposition of the solid solution at high temperatures and inhibit the recrystallization process. Manganese and copper in specified concentrations cause the formation of dispersoids, which provide fundamental strength requirements. Their increase lowers the conductivity. Zirconia and scandium promote the formation of nanoparticles and contribute to achieving the required strength at elevated temperatures. Increasing their content lowers the conductivity.

Iron and silicon also lower the conductivity, but in the form of the common compounds with eutectic type Al (Fe, Mn) Si manganese, they contribute to structure formation which increases alloy strength.

Boron in the form of nanoparticles with aluminum and in the form of transition metal borides increases the conductivity of the alloy. At the same time, by providing consistent segregation in borderline regions on crystal defects, boron increases ductility and, to a certain extent, accelerates aging kinetics.

Exemplary embodiments of the substance according to the application

The alloys were prepared in an electric resistance oven in aluminum crucibles at a melt temperature exceeding the liquidus temperature by 100 ° C. The feeds were aluminum (99.9%), copper (99.9%), fine-grained double ligatures: Al-Mn, Al-Zr, Al-Sc, Al-Si, Al-Fe, a triple ligature Al-B-Ti and / or a boron-introducing composition (potassium fluoroborate, hexachloroethane, potassium fluoride). The alloy compositions are shown in Table 1. Round blocks were cast in a cylindrical mold. Pulsed magnetic fields (IMF) or weak pulse currents (SIS) were used to stir the melt, to increase its purity (gases, foreign substances), influence on crystallization and deformation.

The maximum deformation temperature did not exceed 400 ° C., for compositions with Cu weight% 0.5-0.85 and Mn weight% 0.5-0.95, the deformation occurred at room temperature. The annealing took place at 350 ° C.

The Vickers hardness was measured according to GOST 2999-75 with translation to N _β and σ _β . The specific electrical resistance and the conductivity were determined according to GOST 6132-79.

As can be seen from the analysis of Tables 1 and 2, Compositions Nos. 1 and 2 after holding for 400 hours at 250 ° C. in comparison with Prototype (Patent No. 2,446,222) differ in higher conductivity, and in Compositions no. 3 and no. 4 by a higher strength limit. Table 1 Chemical composition of experimental alloys No. of the batch Cu Mn Zn Fe Si sc B impurities 1 0.8 0.6 0.12 0.1 0.1 0.12 0.05 0.08 2 0.8 0.6 0.12 0.1 0.1 0.12 0.06 0.08 3 1.5 1.4 0.5 0.3 0.1 0.06 0.15 0.1 4 1.8 1.4 0.5 0.3 0.1 0.06 0.08 0.1 Table 2 Mechanical properties and conductivity of samples after annealing at 250 ºС, 400 hours No. of the batch _σ β, MPa IACS,% 1 170 57 2 190 56 3 260 55 4 280 54 prototype 240 53

The deformable aluminum-based nanostructural alloy according to the application has a higher heat resistance and conductivity.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• RU 2287600 [0003]
• RU 2446222 [0004]

Cited non-patent literature

• " Mechanical engineering. Encyclopedia in 40 volumes »Volume II-3. Non-ferrous metals and alloys. Moscow, Publisher Maschinostrojenie, 2001, pp. 144-156 [0002]

Claims (5)

Aluminum-based heat-resistant conductive alloy containing copper, manganese, zirconium, scandium, iron and silicon, aluminum solid solution and secondary manganese, zirconium and scandium aluminides, characterized in that it additionally has boron with the following component ratio, wt % Copper 0.5-0.85 manganese 0.5-0.95 boron 0.02-0.15 zircon 0.1-0.5 scandium 0.02-0.15 iron 0.01-0, 30 silicon 0.01-0.15 unavoidable impurities 0-0.1, each containing 0-0.003 residual aluminum, boron being present in the structure in the form of nanoparticles of AlB ₂ , AlB ₁₂ , borides (including with inevitable impurities ) having an average size smaller than 50 nm for ensuring a conductivity higher than 54% IACS and a strength limit after 400 hours at 250 ° C. not lower than 160 MPa. Aluminum-based heat-resistant conductive alloy containing copper, manganese, zirconium, scandium, iron and silicon, aluminum solid solution and secondary manganese, zirconium and scandium aluminides, characterized in that they increase in strength after 400 hours at 250 ° C up to 230-280 MPa, additionally having boron with the following component ratio, wt.%: copper 0.9-2.0 manganese 1.0-1.6 boron 0.02-0.15 zirconium 0.1-0, 5 scandium 0.02-0.15 iron 0.01-0.30 silicon 0.01-0.15 unavoidable impurities 0-0.1, each of them 0-0.003 residual aluminum.  An alloy according to claim 1 or 2 additionally containing wt%: cobalt 0.1-0.45 and / or nickel 0.1-0.35, and / or cadmium 0.1-0.3. A process for obtaining deformed alloy ingots according to claim 1 or 2, which comprises melt preparation at a temperature exceeding the liquidus temperature of 100 ° C, characterized in that components are incorporated in the melt in the form of additional alloys having a fine crystalline structure and having a Average size of nanoparticles up to 1500 nm are introduced, wherein when using additional alloys Al-B-Ti or Al-Cu-Mn (Ti), the titanium content in the melt is 0.05 wt.%. Melt according to claim 4, characterized in that the crystallization of the cast semi-finished product and its deformation under the action of a pulse magnetic field and / or weak pulse current is performed.