Assessment of the surface state behaviour of Al71Cu10Fe9Cr10 and Al3Mg2 complex metallic alloys in sliding contacts

Electrochemical measurements and friction measurements during continuous and intermittent unidirectional sliding tests are used to monitor and to evaluate the surface characteristics of two types of metallic materials characterized by a huge unit cell, namely Al71Cu10Fe9Cr10 and Al3Mg2. The modification of the surface characteristics results from the periodic mechanical removal of a surface film during sliding, and the subsequent (electro)chemical re-growth of a surface film in-between successive sliding contacts. Al71Cu10Fe9Cr10 and Al3Mg2 materials were tested in a phosphate buffer solution pH 7 at 25 °C to compare their depassivation and subsequent repassivation behaviour. The Al3Mg2 material was also tested in a 0.1 M KOH solution pH 13 and 25 °C to reveal the role of constituting metallic elements on the surface film formation. The effect of film formation and removal on the coefficient of friction recorded during unidirectional sliding is discussed.