*2.4. Evaluation of Mechanical Properties*

Tensile lap shear tests of different joints were performed using an electro-mechanical universal testing machine (AG-100KNA, SHIMADZU, Kyoto, Japan) and the displacement speed was set at 0.1 mm/min. The tensile performance was expressed as joint failure load, determined as the average of three specimens at each welding energy condition. The micro-morphologies and chemical compositions of the fracture surfaces were analyzed by SEM and EDS. In this present work, the trial experiments had shown that in all the welded joint failure always occurred along the bonding interface. Therefore, it was decided to investigate the phase composition of this region using X-ray diffraction (XRD; D8 Advanced, BRUKER, Karlsruhe, Japan) analysis. XRD was performed at 40 kV and 40 mA with Cu-Kα radiation.
