Analysis of AKS- and lanthana-doped molybdenum wire

The lamp industry uses molybdenum wire in many high temperature, structural applications, for which doped molybdenum wire is an important product because it possesses greater high-temperature strength and a higher recrystallization temperature than undoped molybdenum. Prior studies on aluminum-potassium-silicon (AKS) doped tungsten wire have shown that the dispersion which provides the interlocking grain structure in recrystallized tungsten wire is bubbles of elemental potassium; these enhance incandescent lamp filament life. In doped molybdenum the dispersion can be either potassium bubbles, or solid oxide particles, depending on the processing method. Lanthana-doped molybdenum has been reported to have recrystallization temperatures above those obtained through AKS-doping. Lanthana particles are stable within molybdenum to elevated temperatures because lanthanum has very limited solubility in molybdenum. This paper will describe a series of analyses of lanthana-doped and AKS-doped molybdenum wires of a range of sizes.