High-temperature deformation of supersaturated Al-Sc-Zr produced via melt-spinning and extrusion

Sc and Zr additions in Al matrix offer enormous potential for strengthening at elevated temperatures due to formation of coarsening resistant precipitates. The high-temperature properties of supersaturated Al-0.4Sc-0.4Zr at% alloy, produced via melt-spinning and extrusion, were studied in creep and elevated temperature compression. Given the larger amount of solute resulting from rapid solidification, the elevated temperature compressive strength of the supersaturated Al-0.4Sc-0.4Zr at% was significantly higher compared to dilute Al-0.06Sc-0.06Zr at%. The operating deformation mechanism at elevated temperatures in both alloys was dislocation climb, and the difference in threshold stress was assessed between Al-0.4Sc-0.4Zr at% and Al-0.06Sc-0.06Zr at%. The larger threshold stress in the supersaturated Al-0.4Sc-0.4Zr at% was attributed to the different microstructure due to the processing. The stress exponents and activation energies from the creep tests are consistent with the diffusion-controlled dislocation climb mechanism. The small grain size led to diffusional creep in the low stress regime in both alloys.