IS IT FEASIBLE TO DETERMINE THE BONDING CHARGE-DENSITY OF STOICHIOMETRIC GAMMA-TIAL THROUGH STRUCTURE FACTOR MEASUREMENTS

All the experimental methods for the measurement of structure factors are reviewed with emphasis on determining the electron charge-density distributions of intermetallic alloys, in particular gamma-TiAl. The techniques discussed include X-ray diffraction, X-ray pendellosung methods, gamma-ray diffraction and high-energy electron diffraction (intersecting Kikuchi line, critical voltage and convergent-beam rocking-curve procedures). All these methods (except for electron diffraction) require high-quality single crystals which seem impossible to prepare for equiatomic gamma-TiAl. However, the critical-voltage electron diffraction measurements presented in this work indicate that the 001, 110, 111, 200, 002, 220 and 202 structure factor amplitudes of stoichiometric gamma-TiAl can be determined with sufficient accuracy for a charge-density study provided that great care is taken.