Kouzou Tsunoyama

Sputtering of Iron with Ion Beams of O2+, N2+ and Ar+

The effects of O2+, N2+ and Ar+ bombardment on surface structure of pure iron were studied. The incident ion beam was raster scanned over the surface of the sample. On the surface of the crater produced by Ar+ or N2+, there were a lot of conical protrusions or conical holes. In contrast to this, the surface of the crater produced by O2+ was rather uniform. By observing these craters with an interferoscope, the values of the sputtered atom yield were calculated. The sputtered atom yield for 20 keV O2+ was 0.6 atoms/ion, and the sputtered atom yield for 20 keV N2+ was about 1.1 atoms/ion. In the case of the Ar+ ion beam, the magnitude of the value was in the range of 1~2.5 atoms/ion. From the in-depth analysis of the implanted incident particles, it was found that the O2+ ions penetrated deep into iron matrix and formed the oxygen enhanced layer, which moderated the inhomogeneity of surface structure and made the surface of the crater flat. On the other hand, the buildup of the implanted layer was very poor in the case of the N2+ ion bombardment.

Some Aspects of the Quantitative Interpretation of Sputtered Ion Mass Spectra

The method of quantitative analysis of sputtered ions by means of the local thermal equilibrium model proposed by Andersen was investigated. The two internal standard procedure for the determination of the values of T and Ne- of the plasma did not yield rational values for these parameters. The difficulty of estimating these values lies in the fact that the observed sputtered ion intensities correspond to only a fraction of the electrons participating in the ionization process.

Application of the Ion Microprobe Mass Analyzer to Problems in Steels

Application of secondary ion analysis to iron and steel was investigated by using the ion microprobe mass analyzer. The spatial distribution of light elements was examined. The methods of various sample preparation were compared, and the surface polished with Al2O3 powder was found to be most suitable for in-depth analysis. This technique was applied to analysis of surface segregation of Al in Fe-0.1%Al alloys. In low alloy steels, it was found that the chemical composition of the sample could be determined with good accuracy by measuring the relative ion intensity ratios.