Influence of Ti coatings on the fatigue behaviour of Al-matrix MMCs. Part Ⅰ: fatigue tests and materials characterization

摘要

Fatigue life and endurance limit of Metal Matrix Composites (MMCs), reinforced with ceramic particles, have been remarkably increased by means of thin Ti coatings sputtered at room temperature. The method has been successfully tested for composites of Al alloys (6061, A359, 2618) with different reinforcement particles (Al_2O_3, SiC). Some alloys were prepared by molten metal process, others by powder metallurgy. The positive effect has been observed also by fatigue tests carried out at 200℃, a temperature of interest for the industrial applications of these materials. The improvement of fatigue characteristics of MMCs by Ti coatings has been ascribed to the sealing of external defects which retards crack initiation.