ELECTRON PROBE MICROANALYSIS OF THE DIFFUSION SYSTEMS BETA-TITANIUM-VANADIUM, BETA-TITANIUM-NIOBIUM, AND CHROMIUM-VANADIUM

The diffusions of niobium and vanadium into pure Betatitanium at 1100C have been studied. Concentration versus distance curves for these systems are similar to each other but are skewed and different in shape from the Gaussians expected in self-diffusion. At temperatures between 1050C and 1200C the curves for chromium-vanadium diffusion do approximate Gaussians. Diffusion coefficients for all three systems have been calculated by Matano's method at elemental concentrations from 5 atom-percent to 95 atompercent. Logarithms of the diffusion coefficients D for Beta -titanium with both niobium and vanadium follow a reasonable straightline relationship with the atom-percent of the solute element. The D values range from 3.5 10 to the minus 12th power sq cm/sec at 95 atom-percent Nb to 7.0 x 10 to the minus 10th power sq cm/sec at 5 atompercent Nb, and from 4.5 x 10 to the minus 11th power sq cm/sec at 95 atom-percent V to 5.0 x 10 to the minus 9th power sq cm/sec at 5 atom-percent V. Calculated D values for Cr-V at 1050C, 1100 C, and 1200C are 4.5 x 10 to the minus 14th power, 1.3 x 10 to the minus 13th power, and 5.6 x 10 to the minus 12th power sq cm/sec respectively. A frequency factor, D sub O of 6=4 sq cm/sec and an activation energy, Q, of 71=4 kcal/g atom were also calculated for Cr-V. (Author)