Phase-Species-Dependent Electrochemical and Corrosion Behaviors of Wrought Mg-Y-Zn-Based Alloys

Abstract

The electrochemical and corrosion behaviors of the wrought Mg-Y-Zn-based alloys with different phase species have been systematically investigated to compare the role of phase species in the corrosion performance. The X-Mg12YZn phase contributes a superior corrosion inhibiting effect over the W-Mg3Y2Zn3 phase. The corrosion rate of Mg-Y-Zn alloy bearing X-Mg12YZn phase is 13.09 mm year−1, which is lower than that of the alloy bearing W-Mg3Y2Zn3 phase (16.67 mm year−1). This is because the X-Mg12YZn platelike phase plates are more effective and durable than W-phase particles to release Y element during surface film formation. The small W-Mg3Y2Zn3 phase particles may drop out from the corrosion scale, resulting in the mass loss and breakdown of the protective surface film during the propagation of corrosion into inner layers. The related corrosion mechanism has been discussed in detail.