Experimental investigation and numerical simulation of electrochemical response of Mg-Al-Zn-Ca alloy

This study focuses on the preparation of an Mg-Al-Zn-Ca alloy for biomedical applications and examines the impact of post-casting heat treatments on its electrochemical, thermal and mechanical properties. The alloy's detailed degradation behaviour was examined through immersion tests, potentiodynamic polarisation, and electrochemical impedance spectroscopy in a simulated body fluid. Micro-structural characterisation and phase analysis were performed by optical microscopy, scanning electron microscopy and X-ray diffraction. It has been observed that the cooling rate during post-solutionisation heat treatment significantly influences the evolution of alpha and beta phases and subsequently alters the alloys' mechanical properties and degradation behaviour. The slowest cooling rate in the furnace-cooled sample favoured re-precipitation of the beta phase along grain boundaries and demonstrated the highest hardness and corrosion rate. The representative micrographs of the alloy were numerically simulated using level set scheme in COMSOL (R) Multiphysics software to investigate galvanic corrosion behaviour.