Characteristics of friction stir spot welding of Zr-based bulk metallic glass sheets

In this study, the friction stir spot welding (FSSW) of Zr-based BMG sheets has been investigated using an apparatus which was devised with a CNC milling machine to give a precise control of the friction time and the plunge depth. The variation of vertical load pressing the sheet specimens and the temperature history during friction stirring were measured which are closely related to the deformation behavior of BMG materials at the supercooled liquid region. A characteristic behavior during FSSW of BMG sheets was found. Influences of the plunge speed and plunge depth on the characteristic features of FSSW of BMG sheets were investigated. The micrographic observation and the tensile shear test were carried out to characterize the behaviors of FSSW of BMG sheets. The fractographic analysis at the fracture surfaces was done.