Hybrid thermal stabilization of Zr doped nanocrystalline Cu

Unraveling Thermodynamic and Kinetic Contributions to the Stability of Doped Nanocrystalline Alloys using Nanometallic Multilayers

“…Specifically, we demonstrated the evolution of this initial nonequilibrium configuration to an energetically preferred grain boundary segregated state, which subsequently evolved to nanoscale Au clustering within the boundaries with increasing temperature before succumbing to nanophase separation. The evolving segregation state thus produced different regimes of stability as predicted from the thermodynamic models and provides an explanation for prior observations of this effect, [ 22,33,42,43 ] now bridging the thermodynamics driving solute segregation with the onset of kinetically limited coarsening in systems containing a transition to solute clustering at elevated temperatures. Through the framework developed herein, we have demonstrated a broadly applicable method combining thermodynamic predictions with in situ measurements on metallic multilayers to decouple stability mechanisms and examine their temperature dependence in nanostructured alloy systems.…”

“…Given the dependence of grain boundary segregation on temperature, it has been established in several systems that a transition in the dominant stabilization mechanism can occur through the evolution of the grain boundary segregation state. [22,33,42,43] For example, in nanocrystalline Fe-Zr, a significant body of literature [36,42,44] has demonstrated a transition from a classical thermodynamic argument for stabilization to stability induced by Zener pinning at a critical temperature resulting from the precipitation of Zr-rich intermetallic compounds. Furthermore, Ta-doped nanocrystalline Cu has been shown to exhibit a similar transition, where the driving force for grain growth was initially reduced due to the saturation of grain boundaries with Ta and subsequently followed by the formation of Ta dispersoids kinetically stabilizing the microstructure at higher temperatures due to the increased volume fraction of pinning particles.…”