Experimental investigation on machinability of in situ formed TiB2 particles reinforced Al MMCs

• Machinability of brand new TiB2 particles reinforced Al-MMC were investigated.
• The main tool wear mechanisms are abrasive and adhesive.
• Small surface roughness was obtained compared to SiC/Al MMCs.
• The machinability is better than SiC/Al MMCs.

In situ formed TiB2 particle reinforced aluminum matrix composite is a newly developed material. It has some outstanding properties which make it to be a promising material for industry applications. Since the reinforcement mechanisms of nanometer TiB2 particles are different from the conventional SiC particles, the machinability is still a problem which restricts the application of TiB2/Al MMCs. In this study, tool wear, machined surface quality, and chip shapes for machining TiB2/Al MMCs were investigated experimentally. The major conclusions are: (1) PCD tools are suitable for the machining of TiB2/Al MMCs due to the wear resistance and high surface quality. The main tool wear mechanisms are abrasive and adhesive, followed by diffusion and oxidation wear. (2) Small surface roughness was obtained when cutting this material than that of SiC/Al MMCs. No groove and hole was observed on the machined surface while it is common for SiC/Al MMCs. The surface quality of TiB2/Al MMCs is better than that of SiC/Al MMCs due to the small size of reinforcements and good adhesion at interfaces of reinforcements and metal matrix. (3) The chip shape of TiB2/Al MMCs is similar to non-reinforced aluminum alloy in macro-scale, while similar to SiC/Al MMCs in micro-scale.