The determination of oxygen in aluminium alloys

In recent times, only occasional studies have been carried out to determine the oxygen content of aluminium alloys by means of chemical processes. 

The results of initial attempts (46) to solve the problem by the use of chemical methods of separation, such as gaseous chlorine or bromine/ methanol, for example, do not stand up to critical evaluation any more than those relating to the determination of oxygen in unalloyed aluminium. The bromine-methanol process in particular is subject to a serious systematic error, since it ultimately responds to aluminium amounts, present in the undissolved silicon component of the alloy, as if they were Al O, and thus reports them as oxygen. 

As has been shown by initial comparison tests with activation analysis techniques under the auspices of Eurisotop and BCR Study Groups, good results are obtained with aluminium-silicon alloys - free from magnesium or only containing less than 3000 pg/g of it - if reducing fusion in a stream of carrier gas is employed in the manner suggested by Kraft and Kahles (47) for the analysis of unalloyed aluminium, with the sole difference that the reaction temperature is increased to 1950°C. Like for unalloyed aluminium, the oxygen contents reported are near the detection limit, and only increase to values of a few pg/g at silicon contents of 7 % or more. 

There is no record of attempts to solve the problem by means of vacuum fusion. 

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