Vacuum-fusion determination of oxygen in aluminium and aluminium-aluminium oxide composites

A copper bath-vacuum fusion method for the determination of oxygen in aluminium was modified because the extensive evaporation of copper at the operating temperature gave trouble in a commercial instrument with unlidded crucibles. The evaporation can be decreased by making use of graphite capsules, where the samples and the copper are sealed before being dropped into the hot crucible. The procedure gives good results for specimens of aluminium and of aluminium-aluminium oxide composites, the oxygen content of which ranged from some tens of p.p.m. to some weight percent. The sensitivity of the method is of the order of 20 p.p.m. for sample weights of 100 mg, if copper of very low oxygen content is used.