Novel laser surface treatments on AZ91 magnesium alloy

Laser surface melting is a high-energy surface treatment that allows modification of the microstructure and surface properties of Mg alloys, among many others. In the present work, a high-power diode laser has been used to study the microstructural and mechanical modifications that occur when laser surface treatments are applied to the surface of the AZ91D Mg alloy. By controlling the laser parameters, two types of surface modifications can be obtained. Complete laser surface melting takes place at high input laser energies. At lower input laser energies, selective laser surface melting occurs with modification of only one phase in the microstructure of the alloy; the other phases remain unaffected. These treatments yield different microstructures, imbuing the treated surface with different properties.