Effect of the substrate temperature on the microstructure and texture of Mg90Zr10 (at.%) films deposited by sputtering

The microstructure of Mg90Zr10 (at.%) films obtained by sputtering onto copper substrate at three different temperatures (180, 320 and 350 °C) has been studied. Films exhibited an intense (0 0 0 1) basal plane fibre texture with the fibre axis parallel to the growth direction. Their microstructure consisted of columnar grains growing from the copper substrate to the free surface which is typical of the zone II of the Movchan and Demchishin zone model developed for PVD materials. Nevertheless, the microstructure of films was dependent on the substrate temperature. The grain diameter increased as the substrate temperature was increased. Moreover, the dislocation density inside the grains as well as that piled-up forming sub-grain boundaries decreased as the deposition temperature increased. Although the film growth in zone II is controlled by surface diffusion the larger surface mobility of the atoms as the substrate temperature increased led to changes in the solubility of zirconium. At low substrate temperatures all zirconium was in solid solution. However, at 350 °C the formation of small zirconium particles occurred at grain boundaries.