Exothermics (United States)

Abstract Small amount of TiB 2 (<5 wt%) was added into B 4 C through a novel method that combines the use of sputter deposition and hot pressing. Sputter deposition provided more uniform dispersion of TiB 2 grains with smaller grain sizes as compared to the conventional particulate mixing. Small amount TiB 2 addition demonstrated to be an effective way for improving the fracture behavior and toughness of B 4 C while not sacrificing its outstanding lightweight property to a large extent: 2.3 wt% TiB 2 addition brought 15% improvement in indentation fracture toughness while resulting in less than 2% increase in density. The improvement can be attributed to the combination of crack impeding by TiB 2 grains and crack deflection at the B 4 C–TiB 2 interfaces. TiB 2 also played as grain growth inhibitor resulting in a slight increase (2%) in Vickers hardness. Another intention of employing sputter deposition was to modify the grain boundary of B 4 C; however, neither formation of Ti‐containing phase nor Ti segregation has been observed at grain boundaries likely due to the poor wettability of B 4 C.

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