Recrystallization of molybdenum wire doped with lanthanum oxide

Abstract

Recrystallization mechanism of La 2O 3-doped molybdenum wire was investigated. Samples of 1 mm in diameter were annealed for 1 h at various temperatures. Substructures were observed by transmission electron microscopy. Subgrain structures including dislocations of high density and small particles were stable up to about 1650 °C. Upon annealing at 1800 °C large grains with high aspect ratio along the working direction partly developed, though subgrains composed of dislocations simultaneously remained. Additionally, dislocations in the coarsened grain were not perfectly removed due to the pinning effect of second particles. Upon annealing over 2000 °C, on the other hand, elongated grain structures developed in the whole area. It is concluded that the grain coarsening was attributed to the primary recrystallization (subgrain coalescence) involving a rearrangement of dislocations rather than to the secondary recrystallization involving a nucleation process in primary grains.