Improvement of the fatigue behaviour of Al 6061/20% SiCp composites by means of titanium coatings

The present work shows that it is possible to increase the fatigue life and endurance limit of Al 6061/20% SiCp composite by means of coatings of titanium sputtered at room temperature. Coatings seal defects always present on the external surface of the composite, retard crack growth thus lead to a remarkable improvement of fatigue behaviour. The effect of coating thickness on fatigue is discussed with reference to surface state, which has been investigated by scanning tunnelling microscopy (STM).