zn cu alloy possesses many important properties that make it an excellent material for stenting. These include high tensile strength (YS), high micro-hardness and good biocompatibility.
Nanoindentation and corrosion evaluation of Zn-based alloys
A thorough nanoindentation characterization and ion release study was conducted in Hanks’ solution to evaluate the corrosion and mechanical properties of the Zn-Cu and Zn-Mg alloys. Corrosion experiments showed that the addition of Mg or Cu ions at the matrix refined the microstructure of the Zn-based alloys and enhanced yield strength (YS) and ultimate tensile strength (UTS) proportional to the volume fraction of secondary phases.
Moreover, the hardness of the e-CuZn5 intermetallic phase exhibited enhanced values compared to pure Zn and Zn-Mg. The higher values of the Vickers micro-hardness were attributed to the increase of the volume fraction of the e-CuZn5 eutectic phase.
The deposition time and electrode potential during EDRR measurements were also investigated to understand the effect of the diffusion limitation in the ED step (t1) and the spontaneous replacement of zinc with Cu2+ ions in the RR step (t2). In general, longer t2 was required to achieve compact microstructures as more Zn is replaced by Cu ions during this deposition time.
During the EDRR, the deposited zinc in the first ED step was spontaneously replaced by Cu2+ ions during the RR step via a potential difference of 1.1 V. Thus, the redox potential of the ED step is essentially a function of the ion exchange process between the deposited zinc and the native Cu2+ ions.