The effects of alumina reinforcement and nickel activated sintering on nanosized tungsten matrix

- Co-reinforced tungsten compacts showed improved strength with high densification.
- 98% of theoretical density was achieved with 0.6 wt% Ni addition.
- Microhardness increased about 32% compared to that of no Al2O3 addition.
- Al2O3 particles uniformly-dispersed in grain boundary to suppress grain growth.
- There exists proper Al2O3 content to improve the hardness more efficiently.

In this work, the effects of aluminum oxide reinforcement and Ni activated sintering on nanosized tungsten matrix was investigated by analysis obtained W compacts sintered at 1400 °C for 1 h. Experimental results show that the effect of alumina reinforcement on tungsten compacts exhibit improved mechanical strength with high densification at relatively low sintering temperature during nickel activated sintering process. The densification of sintered compacts could be effectively enhanced with Ni addition, and near-full dense samples (98.0% of theoretical density) could be obtained by 0.6 wt% Ni adding. Furthermore, the grain growth of sintered compacts could be restrained from 10.55 μm to 2.57 μm with ultrafine Al2O3 addition, which results in about 32% improvement of Vickers microhardness value of 515 ± 7 (VHN) compared to that of W-Ni composite without Al2O3 addition. The results well illustrate the advantage of alumina reinforcement of nanosized tungsten matrix under nickel activated sintering process for their structural applications.