Exploring the fatigue strength improvement of Cu-Al alloys

As a significant scientific problem directly impacting on the long-term safety of engineering materials and facilities, the improvement of fatigue strength under fully-reversed cycling was comprehensively explored in this study. Advantageous material characteristics for the improvement of fatigue strength were summarized from the achievements of the previous researches, followed by a new attempt to combine them in material design. As the model material, alpha-Cu-Al alloys with clean ultrafine-grains as well as large proportions of twin boundaries were thus produced, which exhibited a notable fatigue strength improvement (up to 155% higher than the coarse-grained counterparts and 40% higher than the counterparts produced by severe plastic deformation). Furthermore, a general principle briefly summarized as localized fatigue damage reduction was proposed based on the analysis of the optimizing methods including microstructure optimization and composition optimization. Accordingly, several recommended features to obtain such high fatigue strength materials were finally listed for further anti fatigue design, such as uniform grains with small size and stable boundaries; low initial dislocation density, and proper alloying composition. Published by Elsevier Ltd on behalf of Acta Materialia Inc.