Abstract:The evolution behavior of TiB₂ particles was studied during laser welding on aluminum metal matrix composites (MMCs) reinforced with TiB₂ particles by a high power laser. X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy spectrum analysis (EDS) were used to analyze the phase, thermodynamics and morphology characteristics of the particles in the weld seam, and the interface reactions between TiB₂ particles and aluminum matrix were also discussed. The results show that partial TiB₂ particles melt and merge into larger ones in the middle of the weld seam and that fracture can be found in larger particles when the scale of TiB₂ cluster is larger than the spot size of laser. Al₃Ti and AlB₁₂ are produced by the interface reaction between TiB₂ particles and Al matrix. The interface reaction of broken TiB₂ particles in the middle of the weld seam is stronger than that at the edge of the weld seam.

Key words: metal matrix composites; TiB₂ particles; laser welding; interface reaction