Spark Sintering Behaviors of TiB₂-10Ni with Elementary Bimodal TiB₂ Powders

抄録

This study investigates the spark plasma sintering behavior of TiB₂-10vol.%Ni powder composites, focusing on the effects of TiB₂ particle size variation on microstructure and toughness. The experimental results confirm that utilizing TiB₂ powders with mixed particle sizes enhances sintering performance and improves fracture toughness. Two types of TiB₂ powders were used: fine TiB₂ powder (STiB₂, ~3 μm) and a mixed powder containing larger TiB₂ particles (LTiB₂, average size ~15 μm). These powders were mixture with Ni powder and using spark plasma sintering preparation of composite material. The sintering behaviors corresponded to the obtained characteristic microstructures, as follows: (1) For 100STiB₂-10Ni, the relative density increased from the lowest temperature compared with others, which corresponds to random distribution of STiB2 and Ni. (2) For 100LTiB₂-10Ni, heterogeneous area consisting of fractured particles by initial loading corresponded to high level in initial relative density. (3) For 50STiB₂+50LTiB₂-10Ni, there were both similar areas to in 100STiB₂-10Ni and 100LTiB₂-10Ni, which correspond to density increase at initial stage and sintering promotion after medium temperature. The highest final density level was obtained by deformation of continuous Ni layer in heterogeneous region, such as100LTiB₂-10Ni. The sintering curve of 50STiB₂+50LTiB₂-10Ni could be explained by the behavior of both 100STiB₂-10Ni and 100LTiB₂-10Ni. Its relative density showed the highest value, and its sintering rate was close to that of pure Ni, which showed a high value. Furthermore, it was found that 50STiB₂+50LTiB₂-10Ni exhibited high fracture toughness values.