Quantitative Phase Analysis of Mixtures Containing α‐, β‐Tungsten and WO 2

For incandescent lamp wire fabrication various powder metallurgical steps are necessary. The stepwise reduction of WO 3 to the tungsten metal powder is one of these. During reduction chemical reactions take place under participation of doping elements (K, Si and Al) causing the structure of non‐sag wires. The origin of secondary β‐W like an indicator for the activity of dopings has been attributed importance. Therefore it has been developed a method for quantitative phase analysis of α‐W, β‐W, WO 2 mixtures consisting of oxidation value determination to establish the WO 2 content and X‐ray phase analysis for a quantitative separation of the α‐W and β‐W content. The influence of extinction effects caused by particle size has been investigated and it is proposed a correction method of the measured integral intensities as a function of half‐width of the (110) α‐W reflex. In regard of the obtained results the formation of the tungsten suboxide W 3 O has been excluded.