Study of friction stir welding between AZ31 Mg alloy and 6061 Al alloy joint using neutron diffraction

Al and Mg alloy each have beneficial characteristics. Welding them is inevitable in any industries including automotive and transportation. The Intermetallic Compound (IMC) is still problematic since it exerts a brittle effect on joint strength. Friction Stir Welding (FSW) is an eminent method that does not change the mechanical properties of the material much compare to other methods. In this study, 6061 Al alloy and AZ31 Mg alloy materials were joint by FSW method and various areas are studied by means of neutron diffraction through High Resolution Powder Diffractometer (HRPD) instrument. The area includes weld metal zone (WMZ), as well as thermo-mechanical affected zone (TMAZ5-Al, TMAZ10-Al, TMAZ15-Al, TMAZ5-Mg, TMAZ10-Mg, TMAZ15-Mg) and base metal zone of both Al (BMZ-Al) and Mg (BMZ-Mg). Neutron diffraction data is analyzed with MAUD software. The result showed peaks of each Al and Mg alloy contributed in the weld metal zone center. It also showed an evolution of the neutron diffraction pattern as the region shifted from the weld metal zone to each Al and Mg alloys direction. Several peaks of IMC phase, Mg17Al12, are found in weld metal zone. The hardness measurement resulted the highest value of 119 HV in WMZ.