Characterization of microstructural changes in an Al-6.8 wt.% Mg alloy by electrical resistivity measurements

Abstract

Microstructural changes in an AlMg6.8 alloy after different thermo mechanical (TMT) and sensitization treatments were investigated by electrical resistivity measurements. The electrical resistivity was most affected by the content of Mg solute atoms in the alpha-Al matrix, due to beta-phase precipitation, while contribution of the dislocation density to the resistivity of the AlMg6.8 alloy was less pronounced. The amount and distribution of the beta-phase precipitated during sensitization were found to be strongly affected by the microstructure developed under the previously applied TMTs, i.e. by the dislocation density and the primary beta-phase particles in the dual (alpha + beta) phase structure. During sensitization of the specimens with a recovered/recrystallized dual (alpha + beta) phase structure, precipitation of randomly distributed, globular beta-phase particles occurred. Sensitization of cold deformed and recrystallized single alpha-Al structures induced beta-phase precipitation in the form of a continuous layer along the shear bands/grain boundaries.