Secondary recrystallization kinetics in molybdenum sheet

The nucleation and growth kinetics of secondary grains with specific orientations in molybdenum sheet doped with CaO and MgO were investigated. Colonies of secondary grain nuclei were formed by Nielsen-type coalescence of the neighbouring primary grains. Subsequently the grain first developed along the top surface of the specimen and then across the sheet thickness. The activation energies for nucleation of the secondary grains with [127]<11 9 1> and [235]<551> orientations were estimated to be 108 kcal mol-1 and 117 kcal mol-1 respectively. The temperature dependence of the grain growth rate G along the top surface was described by G = 6 x 103exp(-74,000/RT) cm s-1 for the [127]<11 9 1> orientation and G = 7 x 103exp(-82,000/RT) cm s-1 for the [235]<551> orientation. (Auth.)