Abstract
The isostatic compaction and hydrostatic extrusion of two atomized powders, namely Alcoa grade 1202 aluminium and Atomet 28 iron, are described and it is shown that the extrusion pressures for these powders may be 50-100 per cent greater than for an equivalent wrought material.
Results of mechanical testing and metallographic and fractographic examinations of the extruded aluminium compacts are presented which show that good bonding can be developed by hydrostatic extrusion at ratios of 6·25 and that the resultant strengths can be higher than that of wrought material of a similar composition. This strength improvement is attributed to the strain hardening undergone by the materials during compaction. An interpretation of the bonding mechanism is also given.
Although it has been shown that isostatic compaction and hydrostatic extrusion can be combined to produce well-bonded bar material from metal powder at room temperature, it is suggested that the method is limited by the very high pressures that would be required to produce materials of commercial interest.
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