Dynamical electron diffraction analysis of lattice parameters, Debye—Waller factors and order in Ti-Al and Ti-Ga alloys

It is shown that higher order Laue zone (HOLZ) measurements under strong zone-axis dynamical diffraction conditions can be used to measure crystal lattice parameters with relatively high precision (∼1 in 103). This method is illustrated for γ-phase Ti-Al and Ti-Ga alloys, and results for Ti-Al are compared with those obtained from X-ray measurements. The relative positions of quantum state excitation rings in the HOLZ beams are used to demonstrate that both TiAl and TiGa are fully ordered. In addition, a novel way is described for the determination of Debye—Waller factors from intensities in the different quantum state rings. This has the particular advantage of enabling independent assessment of Debye—Waller factors for the various atomic species.