A preliminary investigation of nanomechanical and vascular compatibility of phase-engineered CuCoZrNbAl high-entropy alloys for stent-graft applications.

High-entropy alloys (HEAs) have emerged as promising candidates for cardiovascular implants due to their adjustable phase structure and excellent mechanical reliability. However, it remains challenging to achieve both mechanical resilience and biological endothelialization simultaneously. This study engineered CuCoZrNbAl HEAs by adjusting the Al content and thermal processing to explore the relationship between composition, microstructure, nanomechanical, and biological properties for stent-graft applications. Increasing the Al content alongside prolonged heat treatment facilitated the formation of a refined dual-phase microstructure comprising a face-centered cubic matrix and body-centered cubic ZrAl intermetallic domains. Among all tested alloys, the optimized CCZN(Al1.0)-H60 alloy exhibited favorable nanomechanical properties, achieving a contact hardness of 11.2 GPa, a Young's modulus of 186.20 GPa, and a remarkably high H/E ratio of 0.060, alongside a reduced indentation depth of 6.51 nm and reduced hysteretic dissipated energy of 455.52×10-18 J. Furthermore, this alloy displayed enhanced electrochemical stability with a low corrosion current density of 1.53 μA/cm2. Surface homogenization and Al-rich phase stabilization significantly enhanced endothelial cell attachments, supporting cell viability exceeding 100% and preserved migration capacity. The hemocompatibility test indicated a hemolysis rate below 2%, suggesting non-hemolytic behavior. These findings demonstrate that Al-driven phase engineering effectively strengthens local deformation resistance and corrosion stability while supporting endothelial cell growth, highlighting CuCoZrNbAl HEAs as potential candidates for further development of stent-grafts.