Characterization of the High Temperature Dislocation Substructure of Mosi2

The dislocation substructure of polycrystalline MoSi2 deformed in compression at temperatures ranging from 900°C to 1300°C has been investigated. Slip is found to occur primarily by <100> Burgers vectors. A quantitative characterization of the <100> dislocation substructure is developed for several deformation temperatures, including the slip systems present and the relative occurrence of each. Orientation distributions showing the screw/edge character of the <100> dislocations are generated at each deformation temperature. Variations in these distributions with temperature are noted, and the implications of these variations to the deformation behavior of MoSi2 are discussed. Notable observations include the onset of dislocation climb between 900°C and 1100°C, a strong preference for dislocations of mixed character at 900°C, and the complete absence of pure screw dislocations from 900°C to 1300°C.