A NON-DESTRUCTIVE X-RAY FLUORESCENCE METHOD FOR ANALYSIS OF METAL ALLOY WIRE SAMPLES

摘要

Although quantitative analysis of metal alloys is typically accomplished by wet-chemical techniques, complete dissolution of some metal alloys can be difficult. Here, we report an alternative non-destructive energy-dispersive x-ray fluorescence (EDXRF) method for determination of nickel, gold, copper, and silver in metal alloy wires. Sample preparation is simple and consists of mounting wires as a single strand in machined polyethylene sample cups. Wires are analyzed in two symmetrical positions nearly parallel to the x-ray beam, thereby improving the external reproducibility of the analysis. Ideally, standards and samples are matched in terms of chemical composition and diameter. For 50 mil copper-silver wire, four certified reference wires consisting of various copper-silver compositions and matching the unknown diameter were used. However, we also investigated standards of different elemental composition and thickness. For analysis of 25 mil nickel-gold wires, 20 mil NIST standard wires consisting of copper-gold were applied for standardization and compared with certified 25 mil nickel-gold standards. Variations in wire diameter were corrected using an infinite thickness approximation, and nickel intensities were calculated from the copper intensities using a fundamental parameters calculation. The standard curves obtained from both approaches are similar, indicating that wires of varying thickness and composition can be applied as standards. Analysis of copper-silver and nickel-copper wire "unknowns" agrees with certified values to better than 0.3 wt %. We conclude that this rapid, non-destructive method could be a useful alternative to wet-chemical methods for many applications.