科研之友
微信
新浪微博
Facebook
分享链接
摘要
In part I of this work, it was found that titanium (Ti) wire encapsulated within mechanically milled alumina powder and sintered at 1350 degrees C forms potentially useful microcavities due to the consolidation of Kirkendall porosity. Here a series of samples sintered at 1350 degrees C in the range 0-24 h has shown the remarkable way in which these cavities form. The cavity has already started in samples quenched from the top of the heating ramp (0 min at 1350 degrees C). It is surrounded by a diffusion zone similar to 300 mu m in diameter, which does not change size throughout the firing process although the contents change markedly. The diffusion zone microstructure is initially complex with phase sequence TiO(2)/Al(2)O(3)/TiO(2) Al(2)O(3)/Al(2)TiO(5). Microstructure evolution may be summarized as outward growth of the cavity accompanied by inward growth of the Al(2)TiO(5) resulting in a similar to 190-mu m-diameter cavity surrounded by a 50-mu m-thick layer of Al(2)TiO(5). The formation of the cavity and surrounding microstructure is discussed although some features, such as the nucleation of Al(2)TiO(5) in the part of the diffusion zone furthest from the Ti source and the ring of Al(2)O(3), which persists in between Ti-rich parts of the diffusion zone are still poorly understood.
- 出版日期2009-6
