New Progress in Aerospace Aluminium-Antimony Alloys

At the exhibition, both Rusal and Aleris exhibited aluminum-antimony alloys for aerospace applications. If we combine 2xxx Al-Cu-Mg alloys with 7xxx Al- Zn-Mg-Cu alloys were used as the first generation of aerospace alloys, then aluminum-lithium alloys were the second generation, and aluminum-beryllium alloys were the third and current generation. As early as the 1950s, scientists discovered that Sc had a strong effect on the organization of aluminum, and the effect of grain refinement ranked first on any other element. Russia, Ukraine, the United States, and China have made great achievements in the research and production of aluminum alloys containing antimony, especially Russia. They are leaders in both research and material production and application. China Northeastern University, Central South University of Technology, etc. have carried out effective research on aluminum alloy containing antimony, but most of them are tracking type. Northeastern University produced a small amount of small-size Al-Mg-Sc alloy materials by continuous casting and extrusion. A small number of applications were obtained but no mass production and larger applications were formed.

In the past, the main obstacles to the high-volume application of Sc-containing aluminum alloys were the high prices and the difficulty of extracting pure SC2O3, but these problems are no longer present. Because the price of high-purity SC2O3 produced by the United Aluminum Corporation of Russia was reduced to 289 US dollars/kg in May 2016.

Russia United Aluminum Corporation

Aluminum-bismuth alloy

The so-called aluminum-antimony alloy is an aluminum alloy containing trace amount of niobium, and the niobium content is not more than 0.4%. It is also added together with zirconium. Because of the excellent comprehensive performance of Al-Sc alloy, it is a new generation of aerospace vehicle following Al-Li alloy. Lightweight structural materials such as ships and ships are now developing five series of 17 grades of industrial Sc containing aluminum alloys. According to the exhibition, they are:

1. There are more than 20 Al-Mg-Sc alloys with high weldability that cannot be strengthened by heat treatment. The grades are 01515, 01523, 01535, 01545, 01570, etc. Their composition and mechanical properties are shown in Table 1. The most successful research and application.

At this exhibition, Al-Mg alloys containing less than 0.14% Sc from the company's RUSAL is the leader of these alloys, and it is a new generation of Al-Mg-Sc alloys with milestone significance. It has the following advantages:

Low cost. Its Sc content is <0.14%, which helps to reduce costs.

High mechanical properties. The tensile strength (UTS) of the Al-Mg alloy containing trace amounts of Sc is more than 30% higher than that of the 5083 alloy, and the yield strength of the Al-Mg alloy is more than twice that of the 5083 alloy, and the tensile strength of the weld is also greater than that of the 5083. About %, but its elongation is about 4% lower than that of the 5083 alloy.

Good weldability. The weldability of Al-Mg-Sc alloy is comparable to that of a conventional 5xxx alloy, and the mechanical properties of the heat affected zone and weld are almost comparable to that of the base material. Rhodium can form polygonal compounds in the alloy, and has a strong grain refinement, which is very beneficial to improve the mechanical properties.

High corrosion resistance. The corrosion resistance of the Al-Mg-Sc alloy is almost equivalent to that of the 5083 alloy. The thin plate sample is still intact as it was in the 3% NaCl+1% HCl solution for 24h, and no pitting corrosion occurs.

2. Al-Zn-Mg-Sc-based alloys, with 2 grades, 01970 and 01975, with 4.5% Zn~5.5% Zn, 2% Mg, Zn/Mg=2.6, and 0.3% Cu~1.0% Cu , 0.30% (Sc + Zr) ~ 0.35% (Sc + Zr). They have high mechanical properties, T6 material tensile strength Rm = 530N/mm2, elongation A = 8%, a high resistance to spalling corrosion and good weldability and superplasticity.

3. Al-Mg-Li-Sc alloys, two grades 01421 and 01423, are new alloys formed on the basis of Al-5.5Mg-2Li-0.15Zr alloys with high mechanical properties and low density ( 2500kg/m3), the lowest density in high-strength aluminum alloys. The mechanical properties of 01421 alloy: tensile strength Rm = 530 N/mm2, yield strength Rp0.2 = 380 N/mm2, elongation A = 6%.

4. Al-Cu-Li-Sc alloys, 2 grades 01460 and 01464. Composition of 01460 alloy: Al-3Cu-2Li-(0.2~0.3) (Sc+Zr), mechanical properties of T4 material: tensile strength Intensity Rm = 550N/mm2, yield strength Rp0.2 = 490N/mm2, good solderability and low temperature performance, the above mechanical properties at liquid hydrogen temperature rise to 680N/mm2, 560N/mm2, 10% respectively, Russia has used it to make rocket cryogenic fuel tanks.

01464 alloy is the development of 01460 alloy. After deformation heat treatment, it has high strength, plasticity, corrosion resistance, weldability, impact resistance and crack resistance, and has good thermal stability. The tensile strength of the plate is Rm= 560N/mm2, yield strength Rp0.2 = 520N/mm2, elongation A = 9%, can be used to make structural parts that work long-term at 120°C.

5. Al-Zn-Mg-Cu-Sc alloys

The alloy is the highest strength alloy with commercial value at present, and the tensile strength Rm can exceed 800N/mm2. The research of the Wright-Patterson Air Force Research Laboratory in Russia, Ukraine and the United States shows that Al-Zn-Mg- Cu-based alloys add a small amount of Sc and Zr, and the Zn content can exceed the upper limit of generally not more than 7%, thereby greatly improving the properties of the 7xxx-based alloy.

6. Electrolytic production of master alloys

Aluminium alloys containing antimony are added to Sc by the addition of an Al-Sc master alloy. Therefore, the preparation of master alloys is one of the key technologies for producing aluminum-antimony alloys. At present, China, Russia, the United States, and Ukraine, which can produce Al-Sc master alloys, are manufactured using traditional techniques. China can produce master alloys containing 2%, 5%, and 10% Sc, from the exhibition. It was learnt that the original electrowinning process for extracting high-purity SC2O3 by the United Aluminum Corporation of Russia has been put into commercial production. An intermediate industrial production line was built at the Ural Aluminum Plant (UAZ) and preparations for the establishment of a series of electrolytic tanks to meet global demand Demand for highly competitive high-purity yttrium oxide, the global demand for SC2O3 in 2016 is estimated to be 10 to 15 t/a.

The successful development of high-purity SC2O3 electrolysis extraction process has a milestone significance, can improve the quality of aluminum-beryllium alloy, can reduce production costs, promote the application of its materials, reduce equipment quality, reduce energy consumption and protect the environment are of great significance.

Aili Aluminum Corporation

AA5024-H116 Aluminum - Tantalum Alloy

The AA5024-116 aluminum-beryllium alloy sheet manufactured by Aleris Aluminium Koblenz GmbH of Aleris Aluminium has been used to manufacture aircraft fuselage and spacecraft structural parts. All parts can be connected by laser beam welding (LBW) or friction stir welding (FSW). Body parts, whether single or double curved (curvature), can be produced by high temperatures, and workpieces produced by this method will not be distorted or spring back, and the dimensions can be maintained. Accurate, at the same time high cost competitiveness, but also can use the traditional riveting connection.

1. Advantages and Applications

The typical thickness of AA5024-H116 alloy sheet is 1.6mm~8.0mm. It can also be produced in O state. Other specifications can also be produced. Due to the low density of the alloy, it has moderate mechanical strength, high corrosion resistance, strict The dimensional deviation can replace the 2xxx alloy as the fuselage skin material that is the plate, its advantages are: low density, 2650kg/m3; good weldability; excellent damage tolerance; good corrosion resistance; extraordinary creep Creep-formable; fairly high thermal stability; easy-to-recure.

Corrosion resistance test results: Nitric acid mass loss test (NAMLT), according to ASTM G67-04, requirements <15mg/cm2, actual measurement value <6mg/cm2; according to ASTM G44-99 test SCC test, under stress 250N/mm No cracks were found on the 30th day; ASSET was used to make the layer corrosion test. According to ASTM G66-99, the required grade was better than or equal to PC, and the measured value was typically PA.

AA5024-H116 alloy sheet has been certified by AMS, MMPDS, Airbus AIMS 03-04-055.

2. Chemical composition

According to the American Aluminum Association's standards, the registered composition of 5024 alloy (mass%): Si0.25, Fe0.40, Cu0.20, Mn.20, Mg3.9~5.1, Cr0.1, Zn0.25, Ti0. 2, Zr0.03 ~ 0.2, Sc0.10 ~ 0.40, other impurities a single 0.05, a total of 0.15, and the remaining Al.

3. Mechanical properties

The positive elastic modulus of AA5024-H116 alloy is E=72GN/m2, and the elastic modulus of compression is G=74GN/m2. Other mechanical properties are shown in Table 2.

Aluminum alloys containing trace amounts of niobium have great potential for application in aerospace vehicles, and have been used in military equipment and some civilian products (sports equipment, general industry, transportation equipment, etc.).