Publications

Effect of B on the thermal stabilization of cryomilled nanocrystalline Cu–Al alloy

Faculty Author(s): Atwater, Mark A.
Student Author(s): -
Department: AEST
Publication: Materialia
Year: 2019
Abstract: Nanocrystalline Cu86Al12B2 alloy with an as-milled average grain size of ∼11 nm was synthesized by high-energy ball milling at cryogenic temperature. The alloy was then annealed up to 900 °C (or 0.87 Tm of Cu). Microstructural changes with annealing were assessed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and microindentation. TEM investigation indicates that the newly-developed alloy retains its nanoscale grain size after annealing at 900 °C. The present investigation complements our previous findings of the thermal stability of cryomilled binary Cu88Al12 and Cu86Al14 alloys, where excellent thermal stability was observed and attributed to the in-situ formation of nanoscale Cu–Al precipitates and their Zener pinning effect. First principle calculation shows equilibrium in Al–Cu–B prefers segregation of B in the grain boundary of Cu–Al alloy. Superior thermal stability of the Cu86Al12B2 alloy was primarily ascribed to the synergistic grain boundary pinning of CuAl2 and AlB12 intermetallic phases. Moreover, the alloy maintains a higher hardness than both Cu88Al12 and Cu86Al14 alloy. The grain size dependent Hall–Petch strengthening was found to be the dominant mechanism with substantial contributions from solid solution strengthening and Orowan strengthening in annealed state.
Link: Effect of B on the thermal stabilization of cryomilled nanocrystalline Cu–Al alloy