| Grain growth was studied on the straight rolled molybdenum sheet doped with CaO and MgO and compared with that of pure molybdenum sheet. Texture change was also investigated during annealing. Optical, scanning and transmission electron micrographs were observed to link the grain growth with the change of recrystallization texture. The rolling texture consisted of one strong component, {100}$lt;011$gt; and two weak components, {211}$lt;011$gt; plus {111}$lt;011$gt; in doped molybdenum and one strong component, {100}$lt;011$gt; and one weak component, {211}$lt;011$gt; in pure molybdenum. When annealing was done up to 1978℃, the recrystallization texture of pure molybdenum sustained a rolling texture, {100}$lt;011$gt;. However, that of doped molybdenum only retained a rolling texture, {100}$lt;011$gt; at a temperature below 1950℃ and changed into near (211)[011] single crystal over this temperature. Upon annealing at this critical temperature, 1950℃, a new large grain was nucleated rapidly from a rolling plane by Nielsen-type coalescence mechanism and subsequently secondary recrystallization occurred at the expense of small matrix grains. Its orientation was far from approximately 30˚about $lt;100$gt;. |
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