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Irradiated silicon carbide (SiC) exhibits higher carrier content but a decrease in conductivity with increased irradiation. It was theorized that this conflicting data was due to structural damage due to irradiation. This theory was supported by the fact that non-irradiated 50μm thick SiC is transparent for visible light and the higher the irradiation dose, the material of the same thickness became less transparent. However, changes in microscopy and polyforms observed by transmission electron microscopy in SiC due to irradiation were minor. Although existence of different polymorphs of SiC was documented, direct proof of the proposed theory has not yet been achieved. [ABSTRACT FROM AUTHOR]

Structural steels experience aging from fatigue, creep, corrosion, and their combinations. High temperature service accelerates creep and stress-corrosion cracking. Degradation by creep is one of the most serious issues affecting the structural integrity of high-temperature parts in power plants. A nondestructive technique allowing for the evaluation of the materials state and the prediction of remaining life has been required for a long time. Advanced nondestructive wave assessment techniques are being developed using elastic, electronic and magnetic wave perturbations analysis. [ABSTRACT FROM AUTHOR]

Nondestructive techniques are being developed for rapid inspection to estimate the remaining service life for power generating plants. Low frequency impedance measurements with ultrasonic resonant wave enhancement to evaluate the precipitation of carbides and to characterize the different microstructures during aging are being developed. The simultaneous use of a combination of two nondestructive techniques for assessing microstructure evolution is illustrated. [ABSTRACT FROM AUTHOR]

The nondestructive evaluation of nickel titanium (Ni-Ti) alloys for applications such as heat treatment for biomaterials applications (dental) and welding was investigated. Ni-Ti alloys and its ternary alloys are valued for mechanical properties in addition to the shape memory effect. Two analytical approaches were perused in this work. Assessment of the microstructure of the alloy that determines the martensitic start temperature (Ms) of Ni-Ti alloy as a function of heat treatment, and secondly, an attempt to evaluate a Friction Stir Welding, which involves thermo-mechanical processing of the alloy. [ABSTRACT FROM AUTHOR]

Application of nondestructive electronic property measurements to assess the strengthening of Mg2Si precipitates in aluminum A356.2 casting has been demonstrated. The results indicated the evolution of precipitation phase through over aging with increased cooling time or thickness of the cast part. The classical optimum precipitation behavior has been characterized and verified with thermal analysis, thermoelectric power, low frequency impedance, and micro hardness measurements. A proposed practice to use nondestructive electronic property measurement tools to assess aluminum casting for acceptable mechanical properties after mold shake out is presented. [ABSTRACT FROM AUTHOR]

Magnetocorrosion is the altered corrosion behavior, including changes in hydrogen ingress, experienced in the presence of a magnetic field. Laboratory electrochemical hydrogen charging measurements in the presence of a magnetic field indicate a significant increase in magnetocorrosion (including hydrogen content, pitting, and cracking) compared to unmagnetized charging. This research evaluated the thermodynamics and kinetics of corrosion, and evaluated the correlation of magnetocorrosion to microstructure, mechanical properties, and magnetic properties. Proposed thermodynamic models including the effects of spin alignment, magnetostriction, and solute-strain have been developed. [ABSTRACT FROM AUTHOR]

The ability to assess microstructure through quantitative nondestructive evaluation is possible through intelligent use of combinations of intrinsic property measurements. A microstructure rule must be developed to identify the number of measurements necessary to characterize phases and their topology. This paper suggests rules and new methods to classify materials based on electronic structure and response to physical perturbations. An electronic metallographic laboratory that can rapidly characterize materials in-situ on functional or structural materials is in our future. [ABSTRACT FROM AUTHOR]

Measurements of Thermoelectric power (TEP) were used to evaluate microstructural analysis in HSLA steel weldments and retained austenite volume fraction for TRIP steel. First, the measurements of TEP for weld microstructure across weldment have shown good correlation with hardness profile. The different TEP values indicated that changes in weld microstructure can be correlated with TEP values measured. Second, it was demonstrated that retained austenite volume fraction were well correlated to TEP measurements for transformation induced plasticity (TRIP) steels. The results suggest that TEP measurements can be correlated to retained austenite volume fraction for TRIP steels, which do not have same chemical composition and thermal heat treatment processes. The retained austenite volume fraction also was measured by X-ray diffraction (XRD) method. With the introduction of these advanced TEP coefficient measurement techniques, the welding and steel industry will be using analytical tools similar to those instruments applied in the semiconductor industry. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]