Microstructure and Wear Resistance of TiB2/7075 Composites Produced via Rheocasting

In this study, TiB2/7075 aluminum matrix composites were prepared via in situ synthesis. It was found that TiB2 particles are mainly quadrate. Large TiB2 particles (1&ndash
2 &mu
m) agglomerate at grain boundaries, but most of the particles are on the submicron scale. Adding 4.5 wt.% TiB2 particles effectively optimizes &alpha
Al grains in the 7075 aluminum alloy. By combining in situ reinforcing particles with the self-stirring effect of a serpentuator, rheocasting of the 7075 aluminum alloy was achieved in a simple and economical way. The average grain size of the specimen after rheocasting and heat treatment was smaller than 33 &mu
m, and the shape factors were greater than 0.85. The wear resistance of the 4.5 wt.% TiB2/7075 aluminum matrix composite that was prepared via rheocasting and gravity casting was tested with loads of 30, 60, 90, and 120 N at a friction speed of 0.15 m/s for a duration of 30 min. Because of the optimized microstructure and increased hardness, the wear resistance of the 4.5 wt.% TiB2/7075 aluminum matrix composite was significantly better than that of the 7075 aluminum alloy, and the wear resistance of the rheocast TiB2/7075 aluminum matrix composite was better than that of the gravity cast one.