Abstract
The microstructure, electrical properties and microhardness of as-cast and cold rolled AlYb and AlMnYbZr alloys were investigated. The addition of Mn, Yb and Zr has a positive influence on grain size.
A deformed structure of the grains with no changes of their size was observed after cold rolling. The Al3Yb particles coherent with the matrix were observed in the AlYb alloys.
The size of the particles was about 20 nm in the initial state; after isochronal treatment up to 540 degrees C the particles coarsen, and their number density was lower. The deformation has a massive effect on the microhardness behavior until treatment at 390 degrees C, after which the difference in microhardness changes between as-cast and cold rolled alloys disappeared.
Relative resistivity changes show a large decrease in the temperature interval of 330-540 degrees C which is probably caused by a combination of recovery of dislocations and precipitation of the Al-3(Yb,Zr) particles. Precipitation hardening was observed between 100 and 450 degrees C in the AlYb alloy after ageing at 625 degrees C/24 h and between 330 and 570 degrees C in the AlMnYbZr alloy after ageing at 625 degrees C/24 h.