Development of new Al-based nanocomposites by mechanical alloying

Al-based binary (Al-Mg) and ternary (Al-Mg-Zr) elemental powder mixtures were mechanically alloyed to develop new Al-Mg-Zr nanocomposite materials. The phase evolution was studied in the as-milled and heat-treated powders by XRD and TEM/EDS analyses. For the binary Al-Mg alloy, the predominant phase was an Al(Mg) solid solution (SS) and an amorphous phase was not possible to be synthesized. Upon adding 5 at.% Zr to the Al-10Mg blended powder, some free Mg was present in addition to the formation of an AI(Zr,Mg)SS, which transformed to the Al3Zr intermetallic after annealing. When the Zr content was increased a nanocomposite of a solid solution and an intermetallic was obtained with considerable improvement in terms of structural stability and hardness. The presence of an oxide phase at 35% Zr might be responsible for the increased hardness in this particular alloy. (c) 2007 Elsevier B.V. All rights reserved.