A comprehensive study on synthesis behavior of nanostructured Al-Zn-Mg-Cu alloy powder with and without 3 wt.% Al2O3 particles during mechanical alloying

Abstract

The mechanical alloying (MA) process was applied to synthesize nanostructured Al-Zn-Mg-Cu alloy powder and its composite with 3 wt.% Al2O3 particles. Both the alloy and the composite powders were produced by simultaneous milling of the constituents for different milling times (0–50 hours), with fixed milling technical parameters. The produced powders were characterized by the X-ray diffraction (XRD) analysis to detect the generated phases. Also, a scanning electron microscope (SEM) and a transmission electron microscope (TEM) were used to observe the morphologies and measure the crystallite size of the powders, respectively. It was found that during the production of the composite powder, the size of Al2O3 particle changed which led to unexpected outcomes. In the alloy state, the average particle size and the crystallite size were lower and the microhardness values were higher than those in the composite powder. Also, the steady state was achieved after a shorter MA time in the alloy state compared to the composite state. The major reason for these results was the changes of alumina particle size in the composite powders at the first stages of the MA process due to consuming a noticeable amount of energy, which made them ineffective. In addition, the compressibility in the composite powders was lower than that of the alloy powders due to the presence of alumina particles. Moreover, in both powders, the compressibility decreased with increasing the MA time because of the increased work hardening and the reduced flow properties.