EFFECT OF PERIODIC CHEMICAL VARIATION ON THE MECHANICAL-PROPERTIES OF TA FOILS

Acetylene gas was admitted to the chamber over approximately two orders of magnitude of pressure during Ta deposition. Residual gas analysis verified that a reaction between the Ta film and the gas occurred. Auger analysis showed that the carbon in the films could be predicted using a simple pressure-versus-rate equation. The pulsed gas process has been applied to the electron beam gun deposition of Ta. Tensile test specimens a few mu m thick show fracture strengths varying from about 170 to about 860 mPa for pure to highly pulsed runs. The fracture strength loosely follows a Hall-Petch relation relating fracture strength to the time between pulses.