Some Factors Deciding the Non-Sag Grain Structure of Doped Tungsten Fine Wires

摘要

Scanning electron microscopic (SEM) observations on potassium bubbles and the measurement of the orientations of the wire axis for secondary recrystallized grains are made to clarify what plays a significant role in the formation of the non-sag grain structure in doped tungsten fine wires. Bubbles, the mean diameter of which is 23 nm, are present at grain boundaries with a high area density of 10~(13) m~(-2). It is concluded that the formation of the non-sag grain structure, which is characterized by the interlocking and the high aspect ratio of the grains, results mainly from the competitive growth of many nucleated grains through the non-uniformly distributed rows of bubbles which are aligned along the wire axis.