Ultrafast laser micro-welding of glass-ceramic to Fe-36Ni alloy: microstructure and mechanical properties

High-strength micro-welds between glass–ceramic and Fe-36Ni alloy using ultrafast laser were obtained and the microstructure and mechanical properties of the micro-welds were characterized. By using response surface methodology (RSM), key factors governing joint performance were identified, enabling the achievement of a maximum shear strength of 72 MPa—1.9 times that of traditional joining methods such as brazing. The dynamic evolution of the laser-material interaction and associated atomic interdiffusion were analyzed from the perspective of energy distribution. Notably, the interfacial microstructure varied at different regions. At the ablation center, a mechanical interlocking structure with distinct volcanic-like features was observed where the metal plasma ejection was induced. At the region far away from the ablation center, it was observed that the molten glass–ceramic entered the pit formed in the metal side. A mixed fracture of the interface and the base material, showing that significant modification was occurred on the glass–ceramic side. In addition, the formation mechanism of joints at optimal parameters was systematically studied and demonstrated through analysis of ablation plasma sputtering and its spatial distribution characteristics.