Cast magnesium billets, in which various amounts of extruded magnesium powder (EP) phases had been embedded along the longitudinal direction, were extruded. The composite extrusions were tensile tested at temperatures from 20°C to 300°C. The results obtained are as follows:
(1) High proof stress of EP was partly due to the effect of the Orowan interaction between dislocations and dispersed oxide particles and was largely due to the fine-grained structure caused by the dispersed particles.
(2) Over testing temperatures, proof stress of the composite extrusions with up to about 10% of EP was higher than that of the non-composite extrusions (Specimen 0), while ductility of the former was almost equal to that of the latter. However, ultimate tensile stress of the extrusions was not improved by composite forming. The composite extrusions with more than 10% of EP were inferior to Specimen 0 with respect to tensile properties.
(3) EP was quite brittle over testing temperatures. However, the composite extrusions with up to 10% of EP was fairly ductile.
(4) Clear discontinuity, corresponding to fracture of EP, on stress-elongation curves of the composite extrusions was observed at 20°C. At higher temperatures, however, this discontinuity was not observed.
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