Microstructure and mechanical properties of an al-zr-er high temperature alloy microalloyed with tungsten

Abstract

We studied the possibility of improving the coarsening resistance of nanoprecipitates with the L12 structure, in an Al-Zr-Er alloy system, by microalloying with slow-diffusing tungsten (W). Dilute Al-Zr-Er-W alloys with and without Si were prepared, cast and isochronally (3 h steps, from 200 to 600 °C) aged to understand the behavior of W and its interactions with Zr and Er in aluminum. The microstructure of these alloys in the as-cast and aged conditions has been studied over relevant length scales in parallel with electrical conductivity and microhardness measurements. In addition to optical microscopy studies, local-electrode atom-probe tomography analyses are performed to investigate the structure of the age-hardening (L12) nanoprecipitates in selected alloys.