Characterization of in situ mechanically worked PVD Mg–Ti alloys

Abstract

Mg–Ti alloys with up to 46 wt% Ti in solid solution were produced by physical vapour deposition (PVD) with in situ mechanical working. All the alloys exhibited compositional inhomogeneity, columnar microstructures and typical PVD defects. The thermal stability of the solid solutions decreased with increasing Ti content, with the most stable solid solution breaking up above 566 K. The in situ mechanical working reduced porosity by closing pores and flattened surface asperities. The oxide film on the surface of the Mg–8 wt% Ti alloy was Ti-free. The air formed oxide film on the alloys with a Ti content above 8 wt% was identiffied as a mixture of MgO and TiO2 covered by Mg(OH)2 and hydromagnesite at the outermost surface. Magnesium oxide and titanium oxide were also formed at the columnar boundaries that were not affected by the in situ mechanical working. The oxide chemistry was studied using Auger parameter analysis.