|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Deformation and Transitions at Interfaces
||L-57: Interaction of Grain Boundaries with Nano-clusters in Immiscible Alloys
||R. K. Koju, M. Rajagopalan, K. A. Darling, L. J. Kecskes, K. N. Solanki, Yuri Mishin
|On-Site Speaker (Planned)
||R. K. Koju
We report on molecular dynamics simulations and in-situ TEM experiments of curvature-driven grain boundary motion and thermal stability in copper-tantalum alloys with and without coherent Ta-rich nano-clusters. The TEM observations validate that the clusters drastically reduce the boundary mobility by the Zener mechanism and resist coarsening along with the Cu matrix with the increase in temperature. The boundary can eventually detach from an array of clusters by an unzip mechanics, or become permanently pinned. Grain boundary motion in a random Cu-Ta alloy exhibits a dynamic instability whereby it experiences less resistance if it moves fast and more resistance if it moves slowly. In the latter case, Ta grain boundary diffusion causes a segregation or precipitation of clusters, which in turn make the motion even slower. Consequences for thermal stability and local microstructural changes of immiscible Cu-Ta alloys on the unique un-conventional mechanical properties are discussed.