| Abstract |
| The early stage of reactive ball milling of Al and Ti elemental powders in a hydrogen atmosphere was investigated using XRD, PSA, SEM and TEM to find out the formation time of TiH2 phase and the usefulness of this phase in processing of nanocrystalline structure. Brittle TiH2 phase formed by hydriding reaction was essential to reduce grain size and particle size. Both grain size and particle size decreased with increasing Ti content and milling time. Hydriding reaction occurred at initial milling time between 1 and 4 hours. Nano-sized grain began to form at the same time as brittle hydride formed and more milling after 10 hrs milling had a little effect on the further reduction of the grain size. The final structure of nanocrystalline Al-Ti alloy powders was the dispersion of nano-sized TiH2 in nano-sized Al matrix. The grain size observed from TEM micrograph was less than 20 ㎚. During the reactive ball milling of Al and Ti elemental powders in a hydrogen atmosphere, it is found that grain size was first refined to nano-structure and then particle size began to reduce from 45㎛ to 15㎛. |
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| Key Words |
| Reactive ball milling, Hydriding reaction, Titanium hydride nanocrystalline Al-Ti alloy |
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