Aluminium alloys

-          Pure aluminium possesses relatively poor casting characterstics and for this reason castings are produced from aluminium alloys.

-          The principle alloying elements in aluminium base casting alloys are copper, silicon, magnesium, zinc, manganese, chromium, tin, titanium etc. iron may be also be present as an impurity.

-          Copper: copper content of 2 to 5% provides optimum ductility (toughness) whereas greater percentage of copper adds to hardness and strength.

-          Silicon: the general effect of increasing silicon content is to increase the strength (until the eutectic silicon percentage is reached). Ductility is however is lowered.

-          Magnesium: the alloying behavior of magnesium in aluminium is similar to that of copper.

-          Zinc: makes it possible to obtain a maximum of mechanical properties in the as-cast condition.