ALUMINUM-BASED ALLOY

Abstract

The invention relates to the field of metallurgy of aluminum-based materials and may be used for the manufacture of products operating in corrosive environments under high loads, in particular, at elevated and cryogenic temperatures. The new aluminum alloy with a structure comprising an aluminum solution, precipitations and an eutectic phase formed by elements such as magnesium, manganese, iron, chromium, zirconium, titanium and vanadium, is claimed. Besides, the alloy additionally contains silicon and scandium, wherein at least 75% of the share of each element from the group of zirconium and scandium form precipitations with the lattice of type L1.sub.2 in the amount of at least 0.18% vol and the particle size of no more than 20 nm, with the specified redistribution of alloying elements.

Claims

1. An aluminum alloy comprising: an aluminum solution, precipitations, and an eutectic phase formed by one or more of magnesium, manganese, iron, chromium, zirconium, titanium, and vanadium, wherein: the aluminum alloy further comprises silicon and scandium, and at least 75% share of each element from the group of zirconium and scandium of the aluminum alloy form precipitations with a lattice of type L1.sub.2 in an amount of at least 0.18% vol and a particle size of no more than 20 nm, with redistribution of alloying elements (% wt) of: TABLE-US-00006 Magnesium 4.0-5.5 Manganese 0.3-1.0 Iron 0.08-0.25 Chromium 0.08-0.18 Zirconium 0.06-0.16 Titanium 0.02-0.15 Vanadium 0.01-0.06 Scandium 0.01-0.28 Silicon 0.08-0.18 Aluminum and impurities remainder.

2. The aluminum alloy of claim 1, wherein the aluminum alloy is used to manufacture products operating in corrosive environments under high loads.

3. The aluminum alloy of claim 2, wherein, after annealing, the aluminum alloy has mechanical properties including: ultimate tensile strength no less than 350 MPa, yield strength no less than 250 MPa, and elongation no less than 15%.

Description

EMBODIMENTS

[0032] 8 alloys were produced under laboratory conditions, the chemical composition of which is shown in Table 1.

[0033] The alloys were prepared in a laboratory induction kiln, with the mass of each cast of at least 14 kg. The following materials were used as charge materials (% wt): aluminum A99 (99.99% Al), magnesium Mg90 (99.90% Mg), alloying compositions Al-10% Mn, Al-10% Fe, Al-10% Cr, Al-5% Zr, Al-5% Ti, Al-3% V, Al-2% Sc, Al-10% Si. The cross section of cast ingots was 200×50 mm, and the length was about 250 mm. The estimated alloys cooling rate in the solidification range did not exceed 2 K/s.

TABLE-US-00002 TABLE 1 Chemical composition of experimental alloys (% wt) No Mg Mn Fe Cr Zr Ti V Sc Si Al 1 3.8 0.2 0.01 0.01 0.03 0.01 — — 0.25 Bal. 2 4.0 1.0 0.08 0.18 0.06 0.15 0.02 0.28 0.18 Bal. 3 4.1 0.5 0.15 0.10 0.16 0.02 — 0.01 0.09 Bal. 4 5.0 0.6 0.15 0.13 0.10 0.08 — 0.10 0.11 Bal. 5 5.1 0.5 0.16 0.12 0.16 05 0.04 — 0.10 Bal. 6 5.1 0.5 0.25 0.12 0.08 0.08 0.06 0.06 0.08 Bal. 7 5.5 0.6 0.15 0.08 0.10 0.09 — 0.10 0.10 Bal. 8 5.8 1.1 0.27 0.19 0.18 0.17 — 0.31 0.07 Bal.

[0034] Cast ingots were homogenized under the conditions when the maximum temperature of heating and holding did not exceed 425° C. Then hot and cold rolling of ingots into sheets was carried out according to the following scheme: hot rolling temperature 450° C. and total deformation degree 90% down to 5 mm, intermediate annealing of the hot-rolled billet at the temperature of 400° C., cold rolling with the total degree of deformation of 30% down to the thickness of 3.5 mm. The mechanical properties of the sheets were determined after annealing at the temperature of 300° C. for 3 hours, the results of which are shown in Table 2. The mechanical properties were evaluated based on the results of the determination of the ultimate tensile strength (UTS), yield strength (YS) and elongation (El). The gauge length of flat specimens was 50 mm, and the test speed was 10 mm/min.

TABLE-US-00003 TABLE 2 Mechanical tensile properties of experimental alloys (Table 1) after annealing at 300° C. No* YS, MPa UTS, MPa El, % 1 124 282 27 2 283 372 19 3 251 367 21 4 273 382 16 5 264 390 16 6 260 381 15 7 282 394 15 8** — — — *see the chemical composition in Table 1 **rupture in cold rolling

[0035] The amount of precipitations was determined using computational and experimental methods, in particular, using the Thermocalc software package and analysis of the structure of homogenized ingots and annealed sheets of experimental compositions. The results are given in Table 3.

TABLE-US-00004 TABLE 3 Amount of precipitations L1.sub.2 (% vol) and redistribution of Zr, V and Sc among structural components Percentage of the element forming Volume fraction of precipitations with the lattice of precipitation particles type L1.sub.2, % No* L1.sub.2, % Zr Sc 1 0.02 50 — 2 0.76 75 98 3 0.20 91 80 4 0.36 85 95 5 0.24 91 — 6 0.18 81 92 7 0.35 85 95

[0036] The results show that only compositions 2-7 meet the requirements for the level of strength properties. Composition 8 ruptured during hot deformation processing due to the presence of primary crystals of the AL6(Fe, Mn) phase.

[0037] Thus, it is shown that the claimed alloy provides for a high processability during deformation processing, while increasing the mechanical properties of the alloy due to precipitations of the Zr-containing phase with the crystal lattice of type L1.sub.2.

[0038] The scope of protection in the form of the following set of features suggests itself:

[0039] 1. Aluminum alloy with the structure, comprising an aluminum solution, precipitations and an eutectic phase, formed by such elements as magnesium, manganese, iron, chromium, zirconium, titanium, vanadium, characterized in that the alloy additionally contains silicon and scandium and at least 75% share of each element from the group of zirconium and scandium form precipitations with the lattice of type L1.sub.2 in the amount of at least 0.18% vol and the particle size of no more than 20 nm, with the following redistribution of alloying elements (% wt):

TABLE-US-00005 Magnesium 4.0-5.5 Manganese 0.3-1.0 Iron 0.08-0.25 Chromium 0.08-0.18 Zirconium 0.06-0.16 Titanium 0.02-0.15 Vanadium 0.01-0.06 Scandium 0.01-0.28 Silicon 0.08-0.18 Aluminum and unavoidable impurities balance.

[0040] 2. Material based on the aluminum alloy as per claim 1 for manufacture of products operating in corrosive environments under high loads.

[0041] 3. Material as per claim 2, characterized in that it has a high level of mechanical properties after annealing, namely, ultimate tensile strength no less than 350 MPa, yield strength no less than 250 MPa and elongation no less than 15%.