Effect of Periodic Chemical Variation on the Mechanical Properties of Ta Foils

摘要

Acetylene gas was admitted to the chamber over approx. two orders of magnitude of pressure during Ta deposition. Residual gas analysis was used to verify that a reaction between the Ta film and the gas occurred. Subsequent Auger analysis showed that the carbon in the films could be predicted using a simple pressure vs rate equation. The pulse gas process (PGP) has been applied to the electron beam gun deposition of Ta. Tensile test specimens a few micro-meters thick have been produced to show fracture strengths varying from approx. 170 MPa to approx. 860 MPa for pure to highly pulsed runs. The fracture strength loosely follows a Hall--Petch relation fracture strength to the time between pulses. Although diffusion of the carbon smoothes out the chemical period, it is thought that the remaining structure accounts for the strength enhancement. (ERA citation 04:013935)