Microstructure, damping capacity, and mechanical properties of high-Zn-content Al-Zn-Ce-Zr alloys processed by rolling and friction-stir processing
Zhilin Li, C.Y. Liu, Jichang Xie, Yonghao Zhao
Abstract
Al-20wt%Zn-xwt% Ce-0.25Zr alloys (x = 0, 0.1, and 0.5) were manufactured via casting, rolling, and friction-stir processing (FSP). Ce addition caused to the formation of Al 2 CeZn 2 in the Al-Zn-Zr alloys, and volume fraction of the Al 2 CeZn 2 phases increased with increased Ce content. Grain refinement, Al 2 CeZn 2 -phase fragmentation, and Zn-phase dynamic precipitation occurred during deformation in the Al-Zn-Ce-Zr alloys studied. Compared with the rolled alloys, the alloys undergoing FSP exhibited finer and more equiaxed grains, higher recrystallized-grain proportion, smaller low-angle grain-boundary percentage, lower dislocation density , coarser Zn phases, and finer and more dispersed Al 2 CeZn 2 phases. The rolled Al-Zn-Ce-Zr alloys had higher strength but less ductility than the FSP alloys. For any state, the alloys added with 0.1 % Ce had the most comprehensive mechanical properties due to the presence of fine Al 2 CeZn 2 phases in them. The presence of Al/Al 2 CeZn 2 interfaces enhanced the high-strain-amplitude internal friction values of alloys added with Ce. The Ce-containing alloys subjected to FSP exhibited higher room-temperature and high-temperatures internal friction values than the rolled alloys with the same chemical composition due to their uniformity of fine Al 2 CeZn 2 phases, excellent grain-boundary sliding capabilities, and high structure stability at high temperatures.