Composite Materials Research Progress

Recent Advances in Discontinuously Reinforced Aluminum… 293
room temperature for only four passes (Fig. 19(b)). Moreover, the grain boundaries of
submicron grains of the composite are diffused comparing to a well defined structure of Al
grains. The selected area electron diffraction (SAD) patterns of pure Al and the composite
reveal numerous spot features indicating the presence of an array of many ultarfine grains
having random distribution of orientations (insets of Figs. 1(9a)-(b)). The tensile strength of
the composite increases from 97 to 249 MPa after four ECAP passes.
Figure 20. TEM micrograph of Al/5 vol.% Al 2O 3 nanocomposite fabricated by HPT consolidation of
raw material powders under 1.5 GPa [21].
Figure 21. Tensile stress-strain curves of Al samples (1,2) and Al/5 vol.% Al 2O 3 samples (3, 4, 5)
fabricated by HPT consolidation under the pressure of 1.5 GPa and tested at 300 ºC at strain rates of 10 -
4 s -1 (1,3) and 10 -3 s -1 (2, 4) and at 400 ºC at a strain rate of 10 -4 s -1 (5) [21].