Machinability of in situ TiB₂ particle reinforced 7050Al matrix composites with TiAlN coating tool

The ex situ SiC_p/Al composites have been widely and deeply researched so far. However, few papers have been reported on the machinability of in situ TiB₂/7050Al composites, whose material property is superior. Due to the rapid tool wear, the TiAlN-coated tool was used in studying the machinability of in situ TiB₂/7050Al composites. The wear mechanisms of the coating tool and surface integrity of machined workpiece surface were analyzed to investigate the tool performance and material machinability. The results showed that, under cyclical mechanical and thermal shock, the wear mechanisms of TiAlN coating tool were adhesion, scratching, microcrack, and chipping of coat. The feed rate was found to have a dominant effect on the surface roughness, and machining defects such as pit, void, smearing, groove, and crack were found in the machined surface. Besides, it was also found that the cutting force had a great influence on the surface residual stress. From analysis of chips, it was believed that the ductility of in situ TiB₂/7050Al composites was reduced and it showed a little brittleness character with existence of nanometer particles.