Wear Behavior of the Multiheterostructured AZ91 Mg Alloy Prepared by ECAP and Aging

The microstructure design based on the development of heterostructure provides a new way for high strength and ductility Mgalloys. However, the wear property, as an important service performance, of Mg alloys with heterostructure is scarcelyinvestigated. In this work, a high strength and ductility AZ91 Mg alloy with multiheterostructure was preparedviaa processingroute combined industrial-scale equal channel angular pressing (ECAP) and aging. The multiheterostructure consists of theheterogeneous grain structure and heterogeneous precipitates. The dry sliding wear behavior of this multiheterostructured (MH)alloy is investigated compared to the as-cast alloy. The impacts of the applied load and duration time on the wear volume andcoefficient of friction (COF) are analyzed, and the wear mechanism is further discussed. The result indicates that although theMH alloy exhibits high-desirable strength-ductility synergy, it shows a poorer wear resistance but a relatively lower COFcompared to the as-cast alloy at the present condition. The wear mechanism of both alloys mainly involves abrasive wear, aswell as mild adhesion, delamination, and oxidation. In comparison, the MH alloy shows relatively severe adhesion,delamination, and oxidation. The poor wear resistance of the MH alloy at the present dry sliding wear condition is linked to theabundant grain boundaries andfine precipitates. Therefore, one should reasonably use the MH Mg alloy considering the serviceconditions to seek advantages and avoid disadvantages.