These are alloys of Aluminium, which are used in Casting. There have low densities and low melting temperatures. They show little solubility of Hydrogen, which can lead to Hydrogen Embrittlement. These alloys generally have good fluidity, which makes them good materials to cast. The only problem is the shrinkage of the alloys upon cooling.

There are several types of Aluminium casting alloys, with the designation system (from the Aluminium Association) as follows:-

  • 1xx.x 99.00% Aluminium or greater
  • 2xx.x Aluminium-Copper alloys
  • 3xx.x Aluminium-Silicon alloys with Copper and/or Magnesium
  • 4xx.x Aluminium-Silicon alloys
  • 5xx.x Aluminium-Magnesium alloys
  • 7xx.x Aluminium-Zinc alloys
  • 8xx.x Aluminium-Tin alloys
  • 9xx.x Aluminium with other elements added, e.g. Aluminium-Lithium alloys

The number designation above describes the alloy in a general fashion.

  • The first number shows the types of elements added
  • The next two numbers give the minimum percentage of Aluminium in the alloy, so 225, would be an Aluminium-Copper alloy, with 99.25% Aluminium.
  • The last digit gives the product form, where 0 is a casting and 1 is an ingot.