Experimental Analysis of Microstructure and Mechanical Behaviour in Fine Grained Al-Zn-Mg Alloy

The high strength Al-Zn-Mg alloy is widely used for structure components in critical aerospace applications. Small additions of scandium (Sc) often refine cast microstructure and mechanical properties by forming metastable Al3Sc dispersoids. The main role of the Al3Sc dispersoid is to prevent recrystallization during hot deformation and solution treatment. A new technique to apply for surface modification of cast aluminium alloy is usually called friction stir processing (FSP) but basic principle follows by friction stir welding (FSW). The main aim of the present work is to discuss the recent advances in the area of FSPed fine grained aluminium alloy and to highlight the modern trends in research. Highlighting will be focus on the main strategies to increase strength of the fine grained aluminium alloy without loss of ductility, microstructure-property relationship and enhanced mechanical properties, as well as innovative potential of the fine grained aluminium alloys. It is experimentally proven that the higher Zn content (7.35 wt.%) with high Sc content (0.83 wt.%) alloy after FSPed enhanced as much as 0.2%PF 165.5 MPa, UTS 325.2 MPa and ductility 8.5 % respectively. Moreover, several characterizations has been done such as OM, XRD, TEM and fractographs analysis through EDAX and SEM analysis also revealed Al3Sc agglomeration after solution treatment and cavity formation due to Zn vaporization at high rotational speed and traverse speed of FSPed alloys. But mechanisms states that the combined effects of chemical properties, fine grained due to dynamic recrystallization, MgZn2 hardening precipitates and Al3Sc dispersoids of anti-recrystallization results. The several mechanical testing has been done such as hardness measurement along the stir zone, tensile properties and toughness. The aim has to enhance functional properties of aluminium alloy through new innovation technique of FSPed.