Experimental investigation on the effect of process environment on the mechanical properties of AA5083/Al2O3 nanocomposite fabricated via friction stir processing

Friction stir processing, a lately devised grain refining and also microstructure homogenizing technique, has extensively been used on aluminum alloys. Significance of limiting the grain growth during the process, has made lots of researchers make endeavor to keep, as one of the ways of controlling grain growth, the process temperature low; one way of doing so, is performing the friction stir process under water, which keeps the peak temperature low and increases the cooling rate as well. In the present work, research has been done to make known the effects of doing submerged friction stir processing on mechanical properties of AA5083/Al2O3p composite. The process was completed on each sample without changing the rotation and traverse speed of the tool. The pin of the tool was a threaded cylindrical one. Tensile and micro-hardness tests were used to evaluate the effect of the process on these properties of the samples. Also to study the microstructure of the samples, optical microscopy (OM) and scanning electron microscopy (SEM) micrographs were used. The results show that, underwater friction stir process is capable of producing defect-free AA5083/Al2O3p nanocomposite. Analyzing the properties of the processed samples showed that, by significantly reducing the grain size, water environment has positive impact on the mechanical properties of the alloy; And that, Hall-Petch effect is more powerful than Orowan mechanism in enhancing the mechanical properties of the samples.