Creepové chování hliníkových slitin zpracovaných metodou ECAP

This work examines creep behaviour in ultrafine-grained aluminum alloys (with Mg and Sc). The coarse-grained materials were subjected to ECAP (equal-channel angular pressing) at room temperature. The microstructural investigations were performed using transmission electron microscopy (TEM). The experiments show that ECAP reduced the average grain size to ~300 - 400 nm and led to the higher occurrence of high-angle boundaries in comparison with the coarse-grained material. The movement of boundaries and the growth of grains, created by ECAP, was restricted by nano Al3Sc coherent precipitates (up to 10 nm).Constant stress creep tests in compression were conducted at the applied stresses from 10 to 80 MPa and temperature of 473 K . In this work the values of the stress exponent for UFG materials and the unpressed material were determined. creep rates recorded for the as-pressed samples were significantly faster, by about two orders of magnitude, than the unpressed alloys