Annealing response of point defects in off-stoichiometric Mo₅SiB₂ phase

Dislocations and planar faults are found to develop in the Mo₅SiB₂ phase during elevated temperature annealing. The dislocations formed in Mo₅SiB₂ of annealed alloys are mostly edge dislocations with the Burgers vectors of 〈100], 1/2〈111], and 〈110]. For the Mo-rich Mo₅SiB₂ phase that formed in a Mo-10Si-20B alloy, a significant amount of constitutional vacancies is introduced during solidification, and the excess vacancies aggregate and collapse into dislocations. At the same time, these dislocations can act as the heterogeneous nucleation sites for the subsequent Mo precipitation. For the Mo-lean Mo₅SiB₂ phase that formed in a Mo-13Si-28B alloy, the constitutional defects are not significant for the development of dislocations.