Corrosion fatigue behavior of porous Cu-bearing Ti alloy fabricated by selective laser melting

Implants are commonly used to replace damaged bones in the human body. Fatigue failure is one of the most serious issues with implants. Understanding the underlying mechanisms that lead to fatigue failure is crucial in ensuring the longevity of biomaterial implants. In this study, the fatigue behavior of the porous biomaterial Ti6Al4V–6Cu, produced by selective laser melting (SLM) in air and in 0.9 wt% NaCl solution was experimentally investigated. The location of the fatigue crack (FC) initiation point on the cyclic strain curve was determined based on the fatigue cycle change. It indicates that crack initiation is accelerated in a state of high stress, and crack propagation is accelerated in a solution containing 0.9 wt% NaCl. Moreover, in an environment containing 0.9 wt% NaCl, the fatigue fracture is predominantly intergranular and partially transgranular, which is attributed to the brittle failure caused by corrosion fatigue. Additionally, in comparison to the Ti6Al4V sample, the porous Ti6Al4V–6Cu sample has a higher fatigue strength and longer fatigue life due to the effect of the Ti2Cu phase precipitated near the grain boundary and the zigzag propagation of FCs.