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Full-Text Articles in Engineering

Nonmonotonic Effect Of Chemical Heterogeneity On Interfacial Crack Growth At High-Angle Grain Boundaries In Fe-Ni-Cr Alloys, Yuchu Wang, Bita Ghaffari, Christopher Taylor, Simon Lekakh, Carlos Engler-Pinto, Larry Godlewski, Yang Huo, Mei Li, Yue Fan Jul 2023

Nonmonotonic Effect Of Chemical Heterogeneity On Interfacial Crack Growth At High-Angle Grain Boundaries In Fe-Ni-Cr Alloys, Yuchu Wang, Bita Ghaffari, Christopher Taylor, Simon Lekakh, Carlos Engler-Pinto, Larry Godlewski, Yang Huo, Mei Li, Yue Fan

Electrical and Computer Engineering Faculty Research & Creative Works

An intermittent pattern is observed in the modeling of interfacial cyclic-loading crack growth at high-angle grain boundaries in ternary Fe-Ni-Cr alloys. Different from conventional wisdom of stress-intensity factor, the abrupt crack advances are found driven by extreme value statistics - namely, the aggregation of atoms with most compressive residual stresses. In addition, inherently non-affine atomic stress fluctuations are discovered, and the fluctuations peak at intermediate level of chemical heterogeneity, causing the fastest crack growth. Implications of such nonmonotonic mechanism in regard to the origin of intermediate-temperature embrittlement phenomena are also discussed.


Cascaded Sapphire Fiber Bragg Gratings Inscribed By Femtosecond Laser For Molten Steel Studies, Dinesh Reddy Alla, Deva Prasad Neelakandan, Farhan Mumtaz, Rex E. Gerald, Laura Bartlett, Ronald J. O'Malley, Jeffrey D. Smith, Jie Huang Jan 2023

Cascaded Sapphire Fiber Bragg Gratings Inscribed By Femtosecond Laser For Molten Steel Studies, Dinesh Reddy Alla, Deva Prasad Neelakandan, Farhan Mumtaz, Rex E. Gerald, Laura Bartlett, Ronald J. O'Malley, Jeffrey D. Smith, Jie Huang

Electrical and Computer Engineering Faculty Research & Creative Works

This research reports a distributed fiber optic high-temperature sensing system tailored for applications in the steel industry and various other sectors. Recent advancements in optical sensor technology have led to the exploration of sapphire crystal fibers as a solution for sensing in harsh environments. Utilizing a femtosecond (fs) laser, cascaded fiber Bragg gratings (FBGs) were meticulously fabricated within a multimode sapphire optical fiber. These FBGs endowed the system with distributed sensing capabilities and underwent rigorous testing under extreme temperatures, reaching up to 1,800 °C. The study delves into the investigation of the FBG reflection spectrum, facilitated by the development of …


Electrochemical Characterization Of Copper Deposited On Plasma And Thermally Modified Titanium Surfaces, K. S. Teng, J. L. Delplancke, Jiangfan Zhang, T. J. O'Keefe Jan 1998

Electrochemical Characterization Of Copper Deposited On Plasma And Thermally Modified Titanium Surfaces, K. S. Teng, J. L. Delplancke, Jiangfan Zhang, T. J. O'Keefe

Electrical and Computer Engineering Faculty Research & Creative Works

Thin oxide films were grown at temperatures from 373 to 1073 K in plasma and in air on commercially pure titanium substrates. It was determined that the color, thickness, composition, phase, and polarization behavior in a copper electrolyte varied with operating conditions: temperature, oxygen partial pressure, and plasma composition. High-temperature and high oxygen partial pressure plasma produced a thick oxide film. The surface film structure transformed from TiO2 (anatase) to TiO2 (rutile) at a temperature of 600 °C. A lower oxide of the form TinO2n-1, such as Ti2O3 (which may be porous) or possibly Ti3O5, was formed on a thermally …


Etch Patterns On Zone-Refined Fe, M. E. Straumonis, Chang-Soo Kim Jan 1970

Etch Patterns On Zone-Refined Fe, M. E. Straumonis, Chang-Soo Kim

Electrical and Computer Engineering Faculty Research & Creative Works

Upon dissolution of zone-refined Fe in strong acids, mainly three kinds of corrosion patterns were observed in the crystallites of the sections. Regardless of the acids, the {110} plane always appeared on the three patterns in the form of smooth and even steps, ledges, or facets. The {112}, {122}, and {123} planes were also developed but to a much lesser degree. The {100} and {111} planes were not observed because grains of the respective orientation were missing on the sections. Attempts were made to explain the formation of the planes by taking into consideration the reticular density of the planes …