The invention relates to an aluminium alloy used as a coating for surfaces subjected to extreme friction stress, with an aluminium matrix incorporating at least a soft phase and a hard phase, as well as a process for producing the coating. The soft phase and/or the hard phase is essentially finely distributed in the aluminium matrix (20) and at least 80%, preferably at least 90%, of the soft phase or soft phase particles (18) have a mean diameter of a maximum of 3 .mu.m. The aluminium alloy is produced by depositing it on the base (11) by a process of deposition from a gas phase.