The characteristics and dynamics of fused silica-aluminum alloy welding during mJ-level femtosecond laser

Abstract

Recent research has focused on the ultrafast laser welding of metal and glass due to its diverse applications in aerospace, medicine, and optical sensing. However, the significant material property differences between metals and glass, along with strict surface requirements, pose challenges to the development of metal-glass welding and limit its industrial utility. Utilizing high-pulse-energy lasers has proven effective in mitigating these challenges. This study comprehensively analyzes a millijoule (mJ)-level femtosecond pulse laser welding technique applied to aluminum alloy and fused silica, with a primary emphasis on understanding the characteristics and mechanism of joint. During the welding process, aluminum and fused silica mutually diffuse, leading to the formation of five distinct zones at the joint's cross-section. Within the aluminum molten pool in rapid cooling, aluminum grains undergo continuous growth along a temperature gradient and then transform into smaller epitaxial grains with altered grain orientations and HAGBs. An amorphous Al2O3 phase coexists with aluminum, forming a lamellar structure. Besides, silicon nanoparticles and transitional γ-Al2O3 precipitate near the center of the weld. This study examines the underlying causes of these phenomena and provides a detailed discussion of the associated strengthening mechanisms, ultimately resulting in a maximum shear strength of 8.94 MPa.