Aluminium Alloy

Aluminium alloy is an alloy in which aluminium is a main metal. Copper, magnesium, silicon, and zinc are the alloying elements. The two principles of classifications are wrought alloy and casting alloy and both are subdivided into further categories heat treatable and non heat treatable. Cast Al alloy have low tensile strength than wrought alloy, and due to its low melting point cast Al alloy yield cost effective products.

The A-Si is the most important cast aluminium alloy, in which the silicon level is (4.0% to 13%) contributed to give good casting characteristics. Due to the protective layer of aluminium oxide, Al alloy always use to keep visibly shining even in dry environment.  In wet environment, when Al alloy is placed near electrical contact with other metals which has more negative corrosion potentials than Al galvanic corrosion may occur.

Aerospace Alloy

Alloys are mainly composed of two lightweight metals called Al and Mg (magnesium), it has been vital for aerospace manufacturing, Al and Mg alloys both are lighter than other Al Alloys and very importantly it is less flammable, due to presence high percentage of magnesium.  The Aluminium – scandium alloys are the main applications of the metallic scandium by weight and is used for minor aerospace industry components. And the alloy contains the weight by 0.1% and 0.5% of scandium. Some of the sports equipment which is really based on high performance materials are getting used by scandium aluminium alloys e.g. baseball bats, lacrosse sticks, even bicycle frames. Smith and Wesson, the U.S gun maker produces revolvers with frames are composed of scandium alloy.

Consideration of Heat Sensitivity

The routine workshop involve more heating is complicated for aluminium, unlike steel; it will melt without glowing into red. Therefore blowing torch is used, because no visual signs will reveal how close the material is melting.  When Al is over heated, it subjected to internal stress and strains; the metal has the tendency to creep under these stresses.

For this reason the aerospace industry avoids, heating the joining parts altogether with adhesives or mechanical fasteners.  During 1970 some of the bicycle frames was used adhesive bonding, but unfortunate results when Al tubing got slightly corroded. Heat treating the parts in an oven and gradual cooling it, will relieved the stress in over heated Al.   Due to intolerance to high temperature of Al, it has not included in the use of rocketry. In Aircraft engine, the combustion chambers are constructed with it, where the gas can reach 3500 K.

Questions:

• What is Al alloy?
• Does Aerospace industry is getting use by Al alloy?