Secondary recrystallization in non-sag W filament wires - On the possible role of relative grain boundary character distribution

Microstructural development during annealing of non-Sag W filament wire can be divided into two stages: (I) formation of relatively fine matrix grains and (II) development of massive elongated grains. While (I) was presumably caused by primary recrystallization, abnormal grain growth was responsible for (II). After the matrix grains formed, no significant normal grain growth was observed, possibly indicating effectiveness of pinning from K bubbles. In general, the matrix grains were not so different in sizes, which possibly minimizes, if not totally rule out, the role of grain size as the deciding criteria for abnormal grain growth. The large elongated grains had significantly higher proportion of grain boundaries.status: publishe