• PDF / 7,129,005 Bytes
• 7 Pages / 595.276 x 790.866 pts Page_size
• 5 Downloads / 313 Views

DOWNLOAD

REPORT

---

ATOMIC FORCE MICROSCOPY IN METALLOGRAPHY G. V. Shlyakhova and A. V. Bochkareva

UDC 620.22:620.186

The paper presents the research results of the micro- and nanostructure of the type 30Х13 (AISI 420S) stainless steel based on the atomic force microscopy (AFM) investigations. Using the AFM images, the phase composition of AISI 420S steel is identified by the scanning and optical electron microscopes. The grain size of carbide inclusions and their structural properties are studied in this paper. Keywords: steel, microstructure, grain boundary, martensite, carbides.

INTRODUCTION The main objective of the materials science research is to understand causal links between the properties and structure of metals and alloys, their changes caused by external influences and to create the optimum structural composition with the specified properties. A wide spectrum of cutting-edge techniques such as nondestructive testing, laboratory tests and examination of test samples are currently used for the diagnostic and assessment of the metal properties. Many standards and techniques have been developed decades ago [1]. This largely relates to light microscopy, which utilizes microanalysis since the time of D. Chernov, the founder of metallography [2]. Basic information about the structure of metals and alloys was obtained by Knechtel, et al. [3], who used magnified optical images of metallographic specimens. Recently, light microscopy has been enhanced by the scanning and transmission electron microscopies, and was used in combination with the phase contrast, micro-interference, nearfield scanning optical microscopy, etc. [4–7], that significantly expanded its analytical capabilities. With the combined techniques, metal scientists could accurately analyze the structure and chemical composition of major and secondary phases in alloys as well as investigate the deformation micro- and sub-microstructure of materials [8]. However, all these methods have weaknesses. For example, the diffraction limit in optical microscopy does not allow a resolution of the structural elements with a wavelength of the order of the of the light applied and lower, which is usually ~1 µm. The space resolution provided by electron microscopy is higher, but yields a high labor intensity in fabrication of specimens (thin foils) required for research. Moreover, optical and electron microscopy generate only two-dimensional images of the metallographic specimen surface. A transition to three-dimensional imaging in metallography is indirect and cannot always meet the needs of researchers. This is a reason why materials science lacks in techniques allowing for the quantitative interpretation of the results obtained. Today, modern metallography is based on fundamentally new non-optical techniques that provide various surface feature information, in particular probe microscopy [9, 10]. In most research fields such as materials science, surface physics, and thin-film physics, no study goes without the scanning probe microscopy (SPM) and the creation of nanoscale struc