Kimitaka Sato

Simultaneous determination of metallic elements in precipitates and inclusions extracted from steel by inductively coupled plasma-atomic emission spectrometry

Abstract A study was made about the possibility of extracting complex precipitates, containing carbides, nitrides, intermetallic compounds, from low-alloy steels, high-alloy steels and heat-resistant super alloys by single electrolysis operation, followed by the simultaneous determination of all metallic elements in the precipitates by inductively coupled plasma-atomic emission spectrometry (ICP-AES). As a result, it was found that 4–5 metallic elements, such as Nb, Mo and Cr, whose determination had been considered difficult even by wet chemical analysis, can be simultaneously determined in the dissolved state in which Na2S2O7 and tartaric acid (20%) added for the treatment of precipitates are concomitants. ICP-AES simplifies the analytical operation considerably and shortens the analytical time from about 18 h by conventional methods to about 1 h.

Ion Microprobe Mass Analysis for Iron and Steel Research

The application of an ion microprobe mass analysis to the study of iron and steel making processes was examined with Hitachi model IMA-2 ion microanalyzer (IMA) equipped with specific devices which will be described in the following section. IMA is designed so as to meet the recent requirements in steel research: devices for sample heating, line analysis, step scanning and brittle fracture at low temperature together with photographic systems for the images by use of secondary ion, total ion, and secondary electron. In the study of the application of IMA, the concentration of tin was confirmed just under the fractured surfaces of the iron with 1.5% tin and it was newly found that niobium and vanadium were concentrated around the manganese sulfide in the fractured surface due to hydrogen blistering.

Comparison of defect structures in Fe-Cu alloys by high-speed and low-speed deformation with the detection of Cu precipitates

In order to clarify the effect of deformation speed on the defect structure evolution in bcc metals, Fe-0.15wt%Cu and Fe-0.6wt%Cu alloys deformed at a high strain rate (4.3 10 5 /s) and a low strain rate (67/s) were studied. The positron lifetime and coincidence Doppler broadening (CDB) measurements were carried out to investigate the formation of vacancy-type defects and Cu precipitates before and after annealing. The size and the concentration of vacancy-type defects introduced by high-speed deformation were larger than those by low-speed deformation. The low-speed deformed specimen exhibited the faster recovery of vacancy-type defects. After annealing at 400 , however, the recovery of vacancy-type defects and the formation of Cu precipitates became almost the same for both. This suggests that the recovery of vacancy-type defects introduced by high-speed deformation is easier than that by low-speed deformation because of the high density of sinks for vacancies.

Positron diffusion in icosahedarl quasicrystals

We have analyzed the measured S-parameters as a function of positron incident energy for the icosahedral quasicrystal (QC) Al 71.5 Pd 20.3 Mn 8.2 and Al 70.7 Pd 21.34 Re 7.96 within the framework of the structural model of approximant crystal. Highly resistive icosahedral QC Al 72 Pd 21 Re 7 was investigated by the slow positron beam technique. The result indicated that icosahedral QC Al 72 Pd 21 Re 7 contains a dense distribution of structural vacancy-type sites like another icosahedral QCs. Considerably high structural vacancy densities (on the order of 10 20 cm -3 ) were determined.

Local analysis of free amorphous carbon with electron probe microanalyzer

鋼板の表面に生成あるいは付着した物質のうち,特に従来同定が困難であった極少量で局在している結晶性の低い遊離炭素について,その試料調製法および同定法を検討した.その結果,鋼板上の目的物をアセチルセルロースで抽出し,ベリリウムを用いる蒸着膜レプリカにより試料調製したのち,X線マイクロアナライザー(EPMA)によって特性X線走査像から同定できることを見いだした.本手法は非晶質遊離炭素のほか,窒素や酸素などの超軽元素の同定にも活用できる.