Aluminum silicon alloys' introduction

The application of aluminum silicon alloys

Castings are the main use of aluminum-silicon alloys, although some sheet or wire is made for welding and brazing, and some of the piston alloys are extruded for forging stock. Often the brazing sheet has only a cladding of aluminum-silicon alloy and the core consists of some other high melting alloy.

Features of aluminium silicon

The copper-free alloys are used for low- to medium-strength castings with good corrosion resistance; the copper-bearing for medium- to high-strength castings, where corrosion resistance is not critical. Because of their excellent castability, it is possible to produce reliable castings, even in complex shapes, in which the minimum mechanical properties obtained in poorly fed sections are higher than in castings made from higher-strength but lower-castability alloys.

Main element of high silicon aluminum

Silicon is the main alloying element; it imparts high fluidity and low shrinkage, which result in good castability and weldability. The low thermal expansion coefficient is exploited for pistons, the high hardness of the silicon particles for wear resistance. The maximum amount of silicon in cast alloys is of the order of 22-24% Si, but alloys made by powder metallurgy may go as high as 40-50% Si.