Crystal Viscoplasticity Model of Molybdenum Including the Influence of Silicon in Solid Solution

Molybdenum (Mo)-based alloys offer higher temperature capability than nickel-based superalloys. The challenge of designing these alloys is tailoring the chemistry and microstructure to achieve high-temperature strength, creep and fatigue resistance, and oxidation resistance while maintaining lower-temperature ductility and damage tolerance. Structure-properties modeling tools can be used to identify optimum microstructures. However, one missing element in this tool set is a constitutive model for the more ductile α-Mo phase over the entire temperature range from room temperature to 1,400°C. A crystal viscoplasticity model is developed for α-Mo, including the influence of varying amounts of silicon (Si) in solid solution. The temperature, strain rate, and Si dependence of the deformation behavior needed to determine the model parameters are obtained from new compression experiments.