An investigation of the interatomic bonding characteristics of a Ti - 51at.% Al alloy by X-ray diffraction

Abstract

The lattice parameters and atomic structure factors on an homogenized, binary, Ti-51at.%Al intermetallic alloy were investigated using powder X-ray diffraction procedures. Powder samples were prepared by pulverizing in a mortar and pestle lathe turnings taken from a sample ingot. The powder was then annealed to relieve the induced stress and passed through a U.S. Standard #400 sieve mesh (38 microns). Lattice parameters of the face-centered tetragonal structure determined from XRD peak positions indicated a c/a ratio of 1.020; values of 4.077(A) and 3.997(A) were obtained for c(o) and a(o) respectively. These results are in agreement with previous research into (y)phase TiAl. Measurement of diffracted integrated intensities was accomplished to determine the Debye-Waller temperature factor with a value of B = 0.58 (A) obtained by the Wilson Method. A reduction in expected measured intensities was noted, particularly at lower Braggs angles. This was attributed to extinction based on the results of a powder particle size average of 24.3 microns. Despite the problems of extinction, the observed Debye-Waller factor was judged to be reasonable accurate upon comparison to characteristic temperature and melting point data of the Ti-Al systems.