CHEMICAL-ANALYSIS OF CU-BE-CO ALLOYS USING QUANTITATIVE PARALLEL ELECTRON-ENERGY-LOSS SPECTROSCOPY

Cu-2 wt% Be and Cu-1.87 wt% Be-0.23 wt% Co alloys have been investigat ed using parallel electron-energy-loss spectroscopy. Energy loss spect ra (acquired in the transmission electron microscopy mode) showed that the composition of the Cu-Be gamma-phase is not constant, as predicte d by the current equilibrium phase diagram, since the Be-to-Cu ratio i ncreases as the alloy ageing temperature decreases. Quantitative energ y loss analyses which were also performed on coarse intermetallic prec ipitates in the Cu-Be-Co alloy yielded a composition of about 48 at.% Be, 21 at.% Co and 26 at.% Cu, together with small amounts of the Si a nd Fe impurities. The Cu L23 edges of both the matrix and the gamma-ph ases revealed a distinct change in the near-edge structure as a result of solid-state bonding effects.