Regulating galvanic corrosion and Ni ions release of magnesium and NiTi wires mixed-woven stent via alkali-heat treatment for cerebrovascular application

Hybridizing Mg alloys with NiTi alloys offers a means to combine self-expanding mechanical function with favorable bioactivity for cerebrovascular stents. However, the significant potential difference between Mg and NiTi induces galvanic corrosion risks, thereby limiting the development and application of such devices. This study, focused on woven flow diverters in vascular environments, investigates the use of in-situ alkali-heat treatment to mitigate galvanic corrosion and regulate Ni ions release in Mg/NiTi woven structures. The results indicate that a uniform alkali-heat coating on Mg wires significantly reduces their corrosion current density. Immersion tests and zero-resistance ammeter (ZRA) measurements further confirm that the coating markedly inhibits the initiation and propagation of localized corrosion and effectively decreases galvanic currents. Notably, coupling with coated Mg wires substantially reduced Ni ions release from NiTi alloys, driven by the local pH increase. This research demonstrates that alkali-heat treatment applied to Mg wires in a woven Mg/NiTi stent structure suppresses galvanic corrosion and significantly reduces Ni ion release from the coupled NiTi alloy, offering new insights into the surface design of Ni-containing biomedical implants.