Role of Ambient Oxygen in the Stabilisation of Single Aluminium Alloy Films

AbstractAluminium-based single films were pulled out of a melt using circular wire frames and characterised with respect to their stability under varied conditions. Pure Al, AlSi9 and AlSi9Mg0.6 alloys as well as particle reinforced composites based on the same alloys but adding different amounts of stabilising SiC or TiB2 particles were prepared. The velocity at which films were drawn was varied to investigate their solidification as well as their oxidation behaviour. In order to study the influence of the oxygen content of the foaming atmosphere a chamber was manufactured that allows for pulling single films under defined conditions. It was found that films without Mg were less stable than Mg-containing ones and even the addition of particles to such Mg-free alloys results in no improvement. In contrast, films made of AlSi9Mg0.6 were more stable and required only a small amount of oxygen (> 200ppm O2), but in general some oxygen has always to be present to obtain a stable film. It was found that the more particles are contained in the composite and the slower the film gets pulled, the lower the required oxygen content is