Nondestructive Evaluation of Titanium Alloys. ESCA (Electron Spectroscopy for Chemical Analysis), ISS (Ion Scattering Spectroscopy), and SIMS (Secondary Ion Mass Spectrometry) Examination of Titanium Alloy Solid Surfaces,

This report will begin with the description of the basic principles and instrumentation of ESCA Electron Spectroscopy for Chemical Analysis, ISS Ion Scattering Spectroscopy, and SIMS Secondary Ion Mass Spectrometry. Particular emphasis will be placed on those aspects which are of immediate relevance to the nondestructive evaluation of titanium alloys such as the concept of chemical shift in ESCA, the relative surface probing sensitivities of ESCA, ISS, and SIMS, the depth profiling capabilities of these techniques. Preliminary results show that, even at moderate resolution, oxygen first orbit photoelectron spectra of at least three types of oxygen are obtained for the five different Ti alloy samples. Sputtering of the intense Ti2p photoelectron signals corresponds to an oxide which completely covers the surface of the specimen. Carbon 1s spectra served to monitor the degree of contamination. ISS-SIMS measurements provided a better insight into the OxygenTi ratio on the surface and in the subsurface layers. Preliminary investigations demonstrate the feasibility of in situ studies of fracture surfaces. Instrumental modifications for the execution of such experiments are now in progess. Our conclusion is that, working in ultrahigh vacuum conditions, ESCA-ISS-SIMS combined, perhaps, with conventional mass spectrometry constitute adequate means to analyze the degree of surface and interstitial oxidation of Ti alloys.