Aluminum alloys are alloys in which aluminum (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon and zinc. There are two principal classifications, namely casting alloys and wrought alloys, both of which are further subdivided into the categories heat-treatable and non-heat-treatable. About 85% of aluminum is used for wrought products, for example rolled plate, foils and extrusions. Cast aluminum alloys yield cost effective products due to the low melting point, although they generally have lower tensile strengths than wrought alloys. The most important cast aluminum alloy system is Al-Si, where the high levels of silicon (4.0% to 13%) contribute to give good casting characteristics. Aluminum alloys are widely used in engineering structures and components where light weight or corrosion resistance is required.

　　Alloys composed mostly of the two lightweight metals aluminum and magnesium have been very important in aerospace manufacturing since somewhat before 1940. Aluminum-magnesium alloys are both lighter than other aluminum alloys and much less flammable than alloys that contain a very high percentage of magnesium.

　　Aluminum alloy surfaces will keep their apparent shine in a dry environment due to the formation of a clear, protective layer of aluminum oxide. In a wet environment, galvanic corrosion can occur when an aluminum alloy is placed in electrical contact with other metals with more negative corrosion potentials than aluminum.

　　Aluminum alloy compositions are registered with The Aluminum Association. Many organizations publish more specific standards for the manufacture of aluminum alloy, including the Society of Automotive Engineers standards organization, specifically its aerospace standards subgroups, and ASTM International.

　　Aluminum master alloy is a traditional products mainly used to adjust composition of molten aluminum. It makes aluminum and some metal with melting temperature combing into master alloy by melting method. Thus the melting temperature of the master alloy decrease great. So that the metal can be molten into aluminum in the lower temperature to adjust the content of the molten mass.

　　Adding proper quantity AlTi alloy into the AlSi casting can make the mechanical strength, anti-corrosion and thermal stability much better. The adding crafts is easy and without erosion.