The phases obtained in copper aluminium bronze alloy (Cu-10wt.%Al-2wt.%Fe) cast into apermanent mould were investigated. The parameters examined were the thickness of thegraphite coating of the mould and its pre-heated temperature. The phases α andγ2 were detected as well as the metastable phases β′ and γ′. The intermetallics of the Fe-Al system were obtained in variousstoichiometric compositions. The different cooling rates of the casting led to twomechanisms of transformation into α-phase grains out of the unstable β-phase, one beingnucleation and growth producing needle-shaped grains, the other exhibiting a massivetransformation into spherical grains.

The study of the gaussian parameter ω—the approximate width of a peak at half height—of the intensity curves obtained by means of the Unidirectional Laser Oblique Illumination technique employed in the optical microscopy of materials permits introduction of the concept of variation of a surface pattern at different magnifications. This concept establishes how the surface pattern or topography varies among different areas when different magnifications are used. Diffraction gratings and metallic surfaces which have been subjected to different metallographic procedures are analyzed, using objectives of 8×, 16×, and 32×.