Precipitation behavior of (Mo) phase on dislocations in Mo 5SiB5 phase


The precipitation behavior of a Mo solid solution in a Mo 5SiB2(T2) matrix has been characterized by transmission electron microscopy. The T2 phase has a distinct range of homogeneity and a temperature dependent solubility range. In order to provide for the homogeneity range of the T2 phase, a significant concentration of constitutional vacancies has been proposed as a defect mechanism. Upon annealing, the excess vacancies aggregate and collapse into dislocations, which then act as the heterogeneous nucleation sites for the subsequent Mo precipitation. The formation of the preferential variants of precipitates is discussed in terms of the interaction between the transformation strain upon precipitation and the stress fields around dislocations, as well as the crystallographic mismatch between the Mo precipitates and the T2 matrix.

Document Type

Conference Proceeding


Dislocation, Heterogeneous Nucleation, Precipitation, Vacancy

Publication Date


Journal Title

Proceedings of an International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2005