Measuring metal homogeneity in a matrix via the measurement of the ratio metal to matrix oxide using ICP-MS

A simple method has been developed that allows a fast determination of the homogeneity of an element M in an alloy, even for minor components. This is done by measuring a ratio of ion currents I, I-M/I-M'O, whereby M' is the matrix element, by inductively coupled plasma mass spectrometry (ICP-MS). T he method can be used to determine the homogeneity of one component in a bi nary alloy and allows to estimate the sample size necessary to minimise unc ertainty contributions due to inhomogeneity in the analysis of such an allo y. In this work the homogeneity of a niobium/0.1% zirconium alloy was deter mined on 1 mg samples. Accurate weighings of these small samples are not re quired, as the method is based on the measurement of the niobium/zirconium amount ratio in the dissolved samples. As this ratio is fairly large, the Z r/NbO amount ratio was measured instead to decrease the magnitude of the me asured ratio. This ratio was found to be sufficiently stable over time for homogeneity testing. In this particular case the Zr/NbO ratio in the sample s was found to vary by 0.049 relative for a 1 mg samples size.