Application of equal-channel angular pressing for producing superplastic aluminum alloys

The equal-channel angular (ECA) pressing technique was used to process two different Al alloys. Different routes were performed to observe the effect of the ECA procedure parameters. Observations by transmission electron microscopy (TEM) showed that a fine-grained structure was introduced in all processed alloys when there was a sufficient amount of strain. Mechanical tests performed at low temperatures and relatively fast strain rates demonstrated that very large ductility may be achieved. This paper describes results obtained on Al-5%Zn and Al-5.5%Mg-2.2%Li-0.12%Zr alloys. The first material showed the appearance of subgrains after a small strain was introduced, followed by an evolution of the structure into an array of high angle grain boundaries. The second material showed the effect of the strain introduced in this complex alloy. In the most successful case, an elongation of more than 1180% was obtained in the Al-Mg-Li-Zr alloy.