Abstract
The DOP-26 iridium alloy (Ir-0.3%W-0.006%Th-0.005% Al) contains a distribution of thorium-containing intermetallic particles, typically less than 1 micrometer in size, which serve to pin grain boundaries. The alloy is thus subject to secondary recrystallization during long-term exposure at elevated temperature if prior plastic strains are within a critical range. A finite element method was used to model the deformation and resulting local plastic strains introduced by sizing operations on recrystallized iridium alloy cups. The results of the analysis show that local strains introduced by the deformation of cups are in all cases maintained below 0.025, the lower critical level for secondary recrystallization at 1600 K. The effects of die clearance and applied load on local plastic strain values were also treated.
