Abstrakt
The effect of hot extrusion at 350 degrees C on microstructure, thermal, electrical and mechanical properties of the AlMnScZr alloy was studied. The samples of the cast and of the hot-extruded alloys were annealed from 20 degrees C up to 600 degrees C.
Transmission and scanning electron microscopy and electron backscatter diffraction examinations of specimens quenched from temperatures of significant resistivity changes were used to identify microstructural processes responsible for these changes. The cast as well as hot-extruded alloy is characterized by a dispersion of fine coherent Al3Sc and/or Al3(Sc,Zr) particles, and furthermore the fine (sub)grain structure was observed in the hot-extruded alloy.
Microhardness HV1 and resistivity values reflect different microstructure of the alloys accordingly. The distinct resistivity changes of the alloys are mainly caused by precipitation of Mn-containing particles.
The apparent activation energy for the Al6Mn-phase precipitation in the hot-extruded alloy was also determined. The obtained results agree with those observed in the alloys prepared by powder metallurgy studied in our previous work.