DISLOCATION SUBSTRUCTURES OF ALUMINIUM-MAGNESIUM ALLOYS DURING THERMOMECHANICAL PROCESSING

摘要

The dislocation substructures during thermomechanical processing have been investigated using four high purity aluminium-magnesium alloys, Al-0.13%Mg, Al-1%Mg, Al-3%Mg and Al-5%Mg. The experimental materials were deformed in a plane strain compression testing machine at 385°C and constant strain rates of 2.5/s and 25/s to strains of 1 and 1.2. A decreasing strain-rate from 25/s to 2.5/s was also applied. Transmission Electron Microscopy (TEM) was used to investigate internal dislocation density (ρ_i), subgrain size (δ) and misorientation across subgrain boundaries (θ). Experimental results show that with increasing magnesium content, internal dislocation density and misorientation across subgrain boundaries increase while subgrain size decreases. A relationship of ρ_1~(1/2)δ = c_2 with c_2 = 5 for Al-0.13%Mg and 10 for the other three alloys has been obtained from the present results.