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Silicon particle reinforced aluminum matrix composite is a new type of composite materials, light weight, low thermal expansion, high thermal conductivity, environmental protection and conducive to recovery, etc., and has broad application prospects in the field of aviation, aerospace, electronic packaging. This material silicon particles higher share of the score, once melted, the molten pool of high silicon content, there is often a lot of solidification shrinkage, the organization very thick lath silicon. Greatly deteriorated performance, lost application value. Using laser fill the wire brazing process, the silicon content of 12% of the 4047 Al-Si flux cored wire as filler material, a systematic study of the silicon particle reinforced aluminum matrix composites welding characteristics. First established the spot laser brazing process is particularly important type of groove forms process conditions, from the surface of the molding and the morphology uniformity, the test of the process parameters on the forming and organizations, optimized process parameters, the smooth surface, the weld contains a number of enhancements relative to the connector. An integral element of the weld only aluminum and silicon, and Al-Si no direct metallurgical reactions organizations is the simple primary silicon and eutectic structure. Solution-diffusion welding process silicon material as its crystallization behavior and organizational structure impact. In this paper, based on analysis of silicon dissolution, diffusion, crystallization behavior, the study of the distribution of elements in different parts of the weld silicon under different process conditions, there is form and structure characteristics. It was found that the weld silicon exist in two forms, namely primary silicon and eutectic silicon. The primary-crystal silicon as a granular, diffuse distribution in the weld, the eutectic silicon exhibit different morphologies at different positions at the interface of the elongated needle-like dendrite rendered small short rod in the center of the weld. The study found that such a short rod eutectic silicon eutectic grew up. Finally, to improve early sharp and needle-like crystalline silicon eutectic morphology of the silicon, to avoid sharp corners in fragmented substrate and a uniform weld to obtain the isotropy of the physical properties such as thermal expansion coefficient. Proposed heat treatment and found that appropriate heat treatment process (T = 550 ° C, t = 8 h, cooling in the furnace) needle-like short rod eutectic silicon broken gathered into granular, the sharp corners of the primary silicon passivation, the weld becomes uniform.
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