Measurement of carbon solubility in magnesium alloys using GD-OES

It is shown that the quality of the internal atmosphere in glow discharge lamps has a crucial effect on the carbon measurement. Recipes, including atmosphere quality checking, atmosphere purification by burning dummy samples, prolonged preburning time and frequent drift corrections, are developed to reliably measure carbon content in trace amounts. The carbon solubilities in magnesium, which are in the order of magnitude of tens of ppm, are consequently measured for the first time. A new route of sample preparation of Mg-C alloys is presented to avoid heterogeneity and contamination. The method for evaluating the crater volume was also advanced.