Toshiko Suzuki

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.

Application of SIMS to Analysis of Steels

The mechanical and chemical properties of steels are largely influenced by the concentrations and distributions of impurity elements. A variety of analytical techniques have been applied to analysis of these elements, and it has been proven that secondary ion mass spectrometry (SIMS) is one of the most useful. SIMS has great sensitivity with excellent lateral resolution and can accomplish surface analysis. These capabilities make SIMS a unique technique for solving several metallurgical problems such as corrosion, passivation, toughness and brittleness. The present paper is a brief review of studies performed in our laboratory using an IMMA made by Applied Research Laboratories.

Sputtering of Metals with 20 keV O 2 + ; Characteristic Etch Patterns, Sputtered Atom Yields and Secondary Ion Mass Spectra

In secondary ion mass spectrometry an oxygen primary beam is frequently used because it enhances and stabilizes the yield of secondary sample ions [1,2]. But its role in the process of secondary ion emission is not yet fully understood [3–6].The purpose of the present paper is to investigate the surface structure, sputtered atom yields and secondary ion mass spectra of metals bombarded with O2 +. Accumulation of these fundamental data will help to elucidate the effect of oxygen ion on sputtering and to establish the method of quantitative interpretation of mass spectra.

Quantitative Analysis of Zn-Fe Alloy Electrodeposit on Steel by Secondary Ion Mass Spectrometry

Zn-Fe alloy electroplated steel has excellent corrosion resistance and is used for autobody panels. But the distribution of alloy element in the deposit has marked effect on the corrosion resistance and its precise in-depth analysis is required to determine the construction of the coated layer. Secondary Ion Mass Spectrometry is one of the most useful techniques to accomplish the quantitative in-depth analysis. However the sputter rate of high alloy varies with the concentration of alloy element [1] and it is necessary to anticipate this variation of sputter rate with Fe concentration for Fe-Zn deposit. A new technique based on the calibration curve method [2] was developed to estimate the true quantitative in-depth profile of alloy element in the deposit.