Weld Reaction Characteristics During Direct Picosecond Laser Welding of Glass and Aluminum Alloy

ABSTRACT Joining aluminum alloys directly to glass without an intermediate layer is challenging due to the alloy's high thermal conductivity, strong chemical reactivity, and the large mismatch in thermal expansion coefficient with glass; moreover, the phase evolution during welding is complex. In this study, quartz glass and 6061‐T6 aluminum alloy were successfully joined using a picosecond laser. With the single‑pulse energy fixed at 10 µJ, the effects of the number of incident pulses on the joint features were investigated. With a shear strength of 32.33 MPa, the optimal shear performance was achieved at 300 kHz. During joint formation, chemical metallurgical reactions between the glass and the metal produced new phases. Driven by vapor pressure and the Marangoni effect, the weld with layered characteristics in morphology and elemental distribution was formed. Adjacent to the metal side, the weld contained a metallic microstructure composed of polycrystalline Al, which reinforced the joint through mechanical interlocking. The interior of the weld comprised a phase mixing zone containing Al 2 O 3 , free Si, free Al, and crystalline SiO 2 , and these freely distributed phases exhibited an oblique drift from the metal side toward the glass side. Based on experimental observations, the mechanism of joint formation was summarized.