Effect of Friction Stir Welding on Bulk Metallic Glasses

In order to enlarge the size of bulk metallic glasses (BMGs), two Cu36Zr48Al8Ag8 BMGs plates were successfully welded by friction stir welding (FSW) without obvious crystallization. The effect of friction stir welding on microstructure and mechanical properties of the BMGs was investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to evaluate the changes of the crystalline particles in the BMGs. Nanoindentation was applied to analyze the changes of the amorphous matrix. Micro-hardness of the stir zone before and after FSW was tested to explore changes of the mechanical properties. Results show that the original Al3Zr particles in the BMGs were refined and some cavities parallel to the rotating direction of the pin were observed in the amorphous matrix after FSW. Furthermore, micro-hardness of the stirred zone rises approximately 50 Hv compared with the as-cast sample due to structure relaxation of the amorphous matrix.