Effects of Mn and Mo Micro-additions on Al-Zr-Sc-Er-Si Mechanical Properties

摘要

Dilute Al-Zr-Sc-Er-Si alloys strengthened by coherent Ll_2 Al_3(Sc, Er, Zr) nanoprecipitates have potential applications at temperatures higher than 400 °C. In this research, the effects of micro-additions of 0.25 at.% Mn and/or 0.10 at.% Mo to a dilute Al-0.08Zr-0.014Sc-0.008Er-0.09Si (at.%) alloy were investigated using atom-probe tomography, as well as mechanical testing after different heat treatments. Molybdenum and manganese result in solid-solution strengthening. Aging at 400 °C leads to the formation of core-shell (Ll_2 structure) nanoprecipitates, with Mn partitioning to the core, and Mo partitioning to both the core and nanoprecipitate/matrix interface. Manganese-modified Ll_2 nanoprecipitates exhibit a higher number density, while Molybdenum-modified Ll_2 nanoprecipitates display an improved coarsening resistance.