Effect of Ti on the Corrosion Behaviour of <i>In Situ</i> Mg₂Si Particle Reinforced Al–12Si-20Mg-XTi Alloys

Abstract

In this study, corrosion behaviour of Al–12Si-20Mg-XTi alloys (Ti content varied between 0 and 4 wt.%) was investigated. Characterizations of the alloys were carried out by microstructural examinations and corrosion tests. Microstructural results showed that precipitation of the Mg2Si phases was observed in Al-12Si-20Mg-XTi alloy matrix as two different morphologies; i.e. as a polyhedral primary particle and as a chinese script. Upon addition of Ti, Al3Ti intermetallic precipitated in the alloy. Corrosion tests were carried out by immersing the alloys in “30 g/l NaCl+10 ml/l HCl” solution. Evaluation of corrosion was determined by measuring weight loss for 24 hours and by potentiodynamic polarization tests. Corrosion resistance of the alloy was approximately constant with 1 wt % Ti addition whereas at higher additions, the corrosion rate increased.