Lattice imperfections studied by x-ray diffraction in deformed aluminum-base alloys: Al-Ge alloy

Abstract

In the present analysis, which is part of a series on a study that has been undertaken on aluminum-base alloys, a detailed X-ray diffraction study of deformation^[1–5] is made on aluminum-base germanium alloys in four different compositions: Al-3.10 at. pct Ge, Al-3.80 at. pct Ge, Al-4.16 at. pct Ge, and Al-4.60 at. pct Ge. The alloys were prepared from spectroscopically pure metals supplied by Johnson-Matthey and Co. Ltd., London, by melting them in graphite crucibles sealed under vacuum in quartz capsules. The alloys were homogenized for 15 days at 400 °C in the face-centered cubic phase (Figure 1), and cold working was performed by careful hand filing at room temperature. The diffractometer samples were prepared in the usual manner,^[3,4] and X-ray diffraction profiles were recorded in a Siemens Kristalloflex-4 X-ray diffractometer using Cu K_α radiation. A portion of the powder obtained by hand filing from each alloy was annealed at 400 °C to relieve strain and was taken as standard for line shift, line asymmetry, and line shape analyses in light of recent developments.^[3,4,6–8] The microstructural parameters, such as coherent domain size (D _e, microstrain 〈∈_L〉, stacking faults α′ and a" (both intrinsic and extrinsic), deformation twin fault β, dislocation density ρ, and stacking fault energy parameter γ/μ, were determined by adopting the same method of analysis and following the same equations that were used before.^[3–7]