Study and characterization of high strength aluminium alloys (2009)

At the beginning of the 20th Century it was discovered that it was possible to increase the mechanical properties of aluminum alloy after a heat treatment just leaving the material at room temperature for some time. It was later concluded that this effect was caused by precipitation hardening followed by aging, which formed a finely dispersed precipitate that was not possible to resolve with an optical microscope. It was not until the development of X ray diffraction and electron microscopy techniques when a real understanding of the precipitate nature was achieved. This process of heat treating is performed following three stages: i) Solid solution treatment, ii) quenching, and iii) aging. The first aluminum alloys developed using this heat treatment where those which used copper (Cu) and Magnesium (Mg). These alloys showed a limited solubility reduction with a temperature decrease. Some researchers have argued that Silver addition to these alloys increases the mechanical properties of the alloys.