Multiple strengthening mechanisms in high strength ultrafine-grained Al-Mg alloys

High strength has always been pursued in binary Al-Mg and 5xxx series Al alloys. However, these alloys usually provide medium strength due to lack of multiple strengthening methods. Here, this study reports on multiple strengthening effects existing in a binary ultrafine-grained (UFG) Al-7.5at.%Mg alloy prepared by mechanical alloying and hot extrusion. Different strengthening mechanisms, in particular, dispersoid strengthening and stacking fault strengthening, are analyzed and evaluated in terms of their respective contribution to the 511 MPa yield strength of the alloy. The strengthening analysis proves that the concurrent generation of nanoscale dispersoids and stacking faults (SPs) can be used as a new microstructural design in developing novel Al-Mg-based alloys with higher strength and enhanced ductility.