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

Abstract

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 α and β 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 β 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^® Multiphysics software to investigate galvanic corrosion behaviour.