Crack growth behavior of AISI-4340 steel during environmental exposure

AISI-4340 is observed to undergo stress corrosion cracking when subjected to a constant load during exposure to a 3.5% NaCl solution. Crack initiation, nucleation, and growth has been monitored as a function of time. Stepped regions consisting of fast and slow crack growth periods are shown to correspond to microstructural changes observed in the fracture surface of the steel. These regions of fast and slow crack rate variations with time show that the crack growth rates do not increase continuously with an increase in the stress intensity

Оценка светового загрязнения с помощью программного комплекса DIALux Evo

Оценка светового загрязнения в городе Томск с помощью программного комплекса DIALux Evo. Анализ осветительных установок и рекомендаций по снижению светового загрязнения.Assessment of light pollution in the city of Tomsk using the DIALux Evo software package. Analysis of lighting installations and recommendations for reducing light pollution

Comparison of electrical CD measurements and cross-section lattice-plane counts of sub-micrometer features replicated in Silicon-on-Insulator materials

Electrical test structures of the type known as cross-bridge resistors have been patterned in (100) epitaxial silicon material that was grown on Bonded and Etched-Back Silicon-on-Insulator (BESOI) substrates. The CDs (Critical Dimensions) of a selection of their reference segments have been measured electrically, by SEM (Scanning-Electron Microscopy) cross-section imaging, and by lattice-plane counting. The lattice-plane counting is performed on phase-contrast images made by High-Resolution Transmission-Electron Microscopy (HRTEM). The reference-segment features were aligned with <110> directions in the BESOI surface material. They were defined by a silicon micromachining process which results in their sidewalls being atomically-planar and smooth and inclined at 54.737{degree} to the surface (100) plane of the substrate. This (100) implementation may usefully complement the attributes of the previously-reported vertical-sidewall one for selected reference-material applications. The SEM, HRTEM, and electrical CD (ECD) linewidth measurements that are made on BESOI features of various drawn dimensions on the same substrate is being investigated to determine the feasibility of a CD traceability path that combines the low cost, robustness, and repeatability of the ECD technique and the absolute measurement of the HRTEM lattice-plane counting technique. Other novel aspects of the (100) SOI implementation that are reported here are the ECD test-structure architecture and the making of HRTEM lattice-plane counts from both cross-sectional, as well as top-down, imaging of the reference features. This paper describes the design details and the fabrication of the cross-bridge resistor test structure. The long-term goal is to develop a technique for the determination of the absolute dimensions of the trapezoidal cross-sections of the cross-bridge resistors reference segments, as a prelude to making them available for dimensional reference applications

Introduction to focused ion beams: instrumentation, theory, techniques and practice

The focused ion beam (FIB) instrument has experienced an intensive period of maturation since its inception. Numerous new techniques and applications have been brought to fruition, and over the past few years, the FIB has gained acceptance as more than just an expensive sample preparation tool. It has taken its place among the suite of other instruments commonly available in analytical and forensic laboratories, universities, geological, medical and biological research institutions, and manufacturing plants. Although the utility of the FIB is not limited to the preparation of specimens for subsequent analysis by other analytical techniques, it has revolutionized the area of TEM specimen preparation. The FIB has also been used to prepare samples for numerous other analytical techniques, and offers a wide range of other capabilities. While the mainstream of FIB usage remains within the semiconductor industry, FIB usage has expanded to applications in metallurgy, ceramics, composites, polymers, geology, art, biology, pharmaceuticals, forensics, and other disciplines. Computer automated procedures have been configured for unattended use of FIB and dual platform instruments. New applications of FIB and dual platform instrumentation are constantly being developed for materials characterization and nanotechnology. The site specific nature of the FIB milling and deposition capabilities allows preparation and processing of materials in ways that are limited only by one's imagination. Introduction to Focused Ion Beams is geared towards techniques and applications. The first portion of this book introduces the basics of FIB instrumentation, milling, and deposition capabilities. The chapter dedicated to ion-solid interactions is presented so that the FIB user can understand which parameters will influence FIB milling behavior. The remainder of the book focuses on how to prepare and analyze samples using FIB and related tools, and presents specific applications and techniques of the uses of FIB milling, deposition, and dual platform techniques. This is the only text that discusses and presents the theory directly related to applications and the only one that discusses the vast applications and techniques used in FIBs and Dual platform instruments

Crack Growth Behavior And Tem Analysis Of Interphase Oxidation In Boron-Enhanced Sic/Sic Composites

A comparison of the crack growth behavior of a silicon carbide-based fiber reinforced, silicon carbide matrix composite (SiCf/SiCm) with or without boron, is presented. The lifetime of boron-enhanced composites was greater than that of the non-boron-containing composite. Transmission electron microscopy (TEM) of the boron-enhanced fracture surface indicates sealing of matrix cracks by an amorphous oxide phase in the sample tested at the lower oxygen level and nearly complete interphase removal in the sample tested at the higher oxygen level. The results indicate the dependence of the acting failure mechanisms on oxygen concentration is distinctly different for the two composites