Natural aluminum and pure magnesium (mg) are completely unsuitable as structural materials for airframes, because they have very low strength. However, when alloyed (chemically mixed) with the other person or with other metals, their strength is vastly improved, and they make up the most widely used group of airframe materials. Alloying metals include zinc, copper, manganese, silicon and lithium, and may be used singly or in combination. perfiles bosch
There are extremely many different variations, each having different properties and so suitable for different uses. Magnesium (mg) alloys are extremely prone to attack by sea drinking water, and their utilization in carrier-based aircraft is generally avoided. Aluminum alloys, although denser than magnesium metals, are less prone to chemical attack, and are cheaper, so might be more widely used. 2024 alloy, known as duralumin, includes 93. 5 percent aluminum, 4. 4 percent copper, 1 ) 5 percent manganese and zero. 6 per cent magnesium (mg), and it is the most generally used of all materials in aircraft structures. Light weight aluminum alloys are more likely to corrosion than natural aluminum, so pure aluminium is often rolled on to the surfaces of their alloys to create a protective layer. The process is recognized as cladding, and bed linens of alloy treated like this are known as clad sheets or Al-clad. Another common means of protecting aluminum alloys is anodising – conversion of the surface layer to a form which is more corrosion-resistant by an electro-chemical process. Aluminum-lithium metals are better than aluminum-zinc and aluminum-copper alloys in strength and stiffness, so can be used to save weight. Their use is limited because they are a couple of times as expensive.
An appealing property which certain light weight aluminum alloys share with ti is they can be super-plastically formed (SPF). The moment the material is warmed to a certain heat, far below its burning point, it is competent of being stretched by several times its own length without tearing or local thinning. It can then be deformed, using an inert gas such as argon, to fill up a mould and take its condition exactly, with no spring-back when the pressure is released. Presently there are various techniques established on this property, which is often used to make extremely complicated shapes accurately and with minimum weight. The high initial cost of tooling means SPF is limited to certain high-cost items, and it is not yet suitable for mass production. Items such as pressure vessels, small reservoirs and reservoirs may be made using this strategy.
Benefits of aluminum and magnesium (mg) metals
1. High strength-to-weight proportions
2. A vast range of different metals, to suit a range of different uses
3. Low density, so better bulk for same weight means they can be utilized in a greater width than denser materials, and therefore are less susceptible to local attachment; this pertains to magnesium precious metals even more than lightweight aluminum alloys
4. Available in many standard forms – sheet, plate, tube, tavern, extrusions
5. Aluminum precious metals are easy to work after simple heat treatment
6. Can be super-plastically formed (certain aluminum precious metals only)
1. Likely to corrosion, so need protective finishes, particularly magnesium (mg) alloys
2. Many precious metals have limited strength, especially at elevated temperature ranges
3. Magnesium alloys have low strength (but high strength-to-weight ratio)
4. No exhaustion limit (see section on fatigue later in this chapter)