Aircraft aluminum alloys

Aluminum has many of the characteristics and qualities required for fluid power lines. Is has high resistance to corrosion and is easily drawn or bent. In addition, it has the outstanding characteristic of lightweight. Since weight elimination is a vital factor in the design of aircraft, aluminum alloy tubing is used in the majority of aircraft fluid power systems. 

Copper, magnesium and zinc at the 1-2% level are normal components of scrap aircraft aluminum alloys. 

A family of acetylene-terminated phenyl quinoxalines have been synthesized by the Polymer Branch of the Materials Laboratory. ( 1) These phenyl quinoxalines are remarkable for their thermooxidative stability and resistance to moisture. These materials have potential for structural applications as adhesives or composite matrix resins.(2) The feature of moisture resistance makes the materials especially attractive for bonding aluminum. However, problems arise from the fact that aircraft aluminum alloys (and their surface oxiges) are altered by exposures to temperatures above 177 C (350 F) and this is much lower than the polymerization temperatures of the acetylene-terminated oligomers. 

Joshua Du Y, Damron M., Tang G., Zheng H., Chu C.J., Osborne J.H. (2001), Inorganic/ organic hybrid coatings for aircraft aluminum alloy substrates . Prog. Org. Coat., 41, 226-232. 

Metallurgy. Lithium forms alloys with numerous metals. Early uses of lithium alloys were made in Germany with the production of the lead alloy, BahnmetaH (0.04% Li), which was used for bearings for railroad cars, and the aluminum alloy, Scleron. In the United States, the aluminum alloy X-2020 (4.5% Cu, 1.1% Li, 0.5% Mn, 0.2% Cd, balance Al) was introduced in 1957 for stmctural components of naval aircraft. The lower density and stmctural strength enhancement of aluminum lithium alloys compared to normal aluminum alloys make it attractive for uses in airframes. A distinct lithium—aluminum phase (Al Li) forms in the alloy which bonds tightly to the host aluminum matrix to yield about a 10% increase in the modules of elasticity of the aluminum lithium alloys produced by the main aluminum producers. The density of the alloys is about 10% less than that of other stmctural aluminum alloys. 

The resistance to corrosion of some alloy sheet is improved by cladding the sheet with a thin layer of aluminum or aluminum alloy that is anodic to the base alloy. These anodic layers are typically 5—10% of the sheet thickness. Under corrosive conditions, the cladding provides electrochemical protection to the core at cut edges, abrasions, and fastener holes by corroding preferentially. Aircraft skin sheet is an example of such a clad product. 

This process, originally designated as RSR (rapid solidification rate), was developed by Pratt and Whitney Aircraft Group and first operated in the late 1975 for the production of rapidly solidified nickel-base superalloy powders.[185][186] The major objective of the process is to achieve extremely high cooling rates in the atomized droplets via convective cooling in helium gas jets (dynamic helium quenching effects). Over the past decade, this technique has also been applied to the production of specialty aluminum alloy, steel, copper alloy, beryllium alloy, molybdenum, titanium alloy and sili-cide powders. The reactive metals (molybdenum and titanium) and... 

Aluminum (Al) is a silver-colored light and soft metal used as a major component of aluminum alloys, which are used to construct aircraft and vehicles, similar to Mg alloys. However, Al is known as a readily combustible metal. Thus, Al particles are used as major fuel components of pyrolants. Al particles are mixed with ammonium perchlorate particles and polymeric materials to form solid propellants and underwater explosives. The reaction between aluminum powder and iron oxide is known as a high-temperature gasless reaction and is represented by ... 

Aluminum is the third most abundant element in the crust of the earth, accounting for 8.13% by weight. It does not occur in free elemental form in nature, but is found in combined forms such as oxides or silicates. It occurs in many minerals including bauxite, cryolite, feldspar and granite. Aluminum alloys have innumerable application used extensively in electrical transmission lines, coated mirrors, utensils, packages, toys and in construction of aircraft and rockets. 

Superplastic—high-strength aluminum alloys which can be plastically shaped into difficult designed parts used on cars and aircraft. 

The casting alloy products comprise sand castings, permanent mold castings, and die castings. Aluminum is the basic raw material for more than 20,000 businesses in the United States. Aluminum is an indispensable metal for aircraft, for example. See Fig. 3. Representative aluminum alloys for a broad classification of uses is given in Table 1. 

It will be seen, therefore, that high surface temperatures can exist at Mach numbers above about 2. These surface temperatures may, in fact, be so high that special high-temperature materials such as titanium alloys rather than conventional aluminum alloys must be used for structural components in aircraft designed to fly at high Mach numbers. 

New aluminum alloys containing 3% lithium with small amounts of zinc and magnesium may supplant 2024 and 7075 in the aircraft wings and fuselage. 

Dealuminification. Recent investigations have shown the importance of the dealloying of S-phase (Al2CuMg) particles on the corrosion of aluminum aircraft alloys, specifically aluminum alloy 2024-T3. In 2024-T3, the S-phase particles represent approximately 60% of the particle population. These particles are of the order of 1 pm diameter, with a separation of the order of 5 pm representing an surface area fraction of 3%.56 The selective removal of aluminum and magnesium from these particles leaves behind a porous copper particle that becomes the preferential site for oxygen reduction.57, (Corcoran)5... 

From Farag 2008 (53), the mass of an aluminum panel that can bear the load in a civilian aircraft is 20.25 kg. The masses of CFRP and CNTRP panels of equivalent stiffness can be estimated from the proportionality of the weight to (p/ E1/3) and the values in Tables 15.5 and 15.6. The values for the aluminum alloy and Epoxy 33% carbon fabric+30% carbon fibers are based on (53). The calculated values are given in Table 15.7. The calculations show that, with the exception of Epoxy+1 wt% CVDMWNT and Epoxy+0.1 wt % MWNT (54), the aluminum panel is heaviest. The cost of material in a panel is calculated from its mass and the cost of material per kg, from Table 15.5. The results show that, with the exception of Epoxy+0.1 wt% MWNT, the aluminum panel is the least expensive. 

The aluminum alloys that have been investigated in the previous sections, including [2B], [7B], and [2A], are materials used for aircraft skins. Aircraft skins are readily... 

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