Consolidation of nanocrystalline Al–5 at.% Ti alloy powders by ultra high-pressure hot pressing

Consolidation behavior of nanocrystalline Al–5 at.% Ti powders has been investigated by using ultra high-pressure hot pressing method. Nanocrystalline Al–5 at.% Ti compacts with full density were successfully processed by hot pressing for 250 s at 120°C under 4.8 GPa with a grain size less than 50 nm. It is considered that each grain in as-compacted materials maintained random orientation with respect to its neighboring grains. The consolidation temperature, 120°C, is about 300–400°C lower than conventional one. Abnormal grain growth was observed in specimens prepared at temperature over 300°C, which was over one half of the absolute melting temperature of Al. Some grains grew up over 500 nm in these specimens. Rockwell hardness and Vickers micro-hardness values of the specimen prepared by the proper conditions were 105.2HRB and 243.7HV, respectively. This hardness value was one of the highest one ever obtained in Al–5 at.% Ti alloys.