There are many reactions that are sensitive to the surface structure of a catalyst. In order to obtain a comprehensive understanding of structure sensitive surface chemistry we use Surface Structure Spread Single Crystals (S4Cs) that expose a continuous distribution of crystal planes across their surfaces. Those crystal planes that lack mirror symmetry contain terraces, monatomic steps, and kinks and can be described as chiral with an R or an S orientation. When coupled with spatially resolved surface analysis techniques, S4Cs can be used to study the effects of surface structure and chirality on surface chemistry across a continuous distribution of crystal planes. A set of six Cu S4Cs has been created that spans all possible crystal planes of Cu. The Cu(111) S4C was used to study the structure sensitivity of L- and D-tartaric acid (TA) decomposition and the Cu(100) S4C was used to study the structure sensitivity of L-4-13C and D-aspartic acid (AA) decomposition. Isothermal Temperature Programmed Reaction Spectroscopy (TPRS) was implemented in which the S4Cs with monolayers of TA and AA were held at a temperature below the temperature of peak decomposition observed in a standard TPR experiment (heating at 1 K/s). At various times during isothermal heating, the surface was cooled to quench the reaction. Spatially resolved X-ray Photoelectron Spectroscopy (XPS) was performed to identify those regions on the surface in which the adsorbates had decomposed and those in which they were still intact. On the Cu(111) S4C which exposes both (100) and (110) step edges, TA decomposition is most sensitive to the density of (100) steps. AA decomposition on the Cu(100) S4C was enantioselective: L-AA-4-13C decomposed on S surfaces before R surfaces while D-AA decomposed on R surfaces before S surfaces. The decomposition of CH3CH2OH, CD3CD2OD, and CF3CH2OH on Zn was studied using temperature programmed reaction spectroscopy (TPRS). The decomposition products of each reaction were determined and a reaction mechanism was proposed for CH3CH2OH decomposition based on the product ratios and peak temperature locations. The CH3CH2OH decomposition mechanism includes the formation of two intermediate species on the surface: CH3CH2- to form CH2=CH2 and CH3CH2O- to form CH3CH=O.

The simulation and design of advanced materials for fatigue resistance requires an understanding of the response of their hierarchical microstructure attributes to imposed load, temperature, and environment over time. For Ni-base superalloy components used in aircraft jet turbine engines, different competing mechanisms (ex. surface vs. subsurface, crystallographic vs. inclusion crack formation, transgranular vs. intergranular propagation) are present depending on applied load, temperature, and environment. Typically, the life-limiting features causing failure in Ni-base superalloy components are near surface inclusions. Compressive surface residual stresses are often introduced in Ni-base superalloy components to help retard fatigue crack initiation and early growth at near surface inclusions and shift the fatigue crack initiation sites from surface to sub-surface locations, thereby increasing fatigue life. To model the effects of residual stresses, inclusions, and microstructure heterogeneity on fatigue crack driving force and fatigue scatter, a computational crystal plasticity framework is presented that imposes quasi-thermal eigenstrain to induce near surface residual stresses in polycrystalline Ni-base superalloy IN100 smooth specimens with and without nonmetallic inclusions. In addition, the effect of near surface inclusions in notched Ni-base superalloy components on MSC growth and fatigue life scatter was investigated in this work. A fatigue indicator parameter (FIP)-based microstructurally small crack (MSC) growth model incorporating crack tip/grain boundary effects was introduced and fit to experiments (in both laboratory air and vacuum) for the case of 1D crack growth and then computationally applied to 3D crack growth starting (1) from a focused ion beam (FIB) notch in a smooth specimen, (2) from a debonded inclusion located at different depths within notched components containing different notch root radii, and (3) from inclusions located at different depths relative to the surface in smooth specimens containing simulated shot peened induced residual stresses. Computational predictions in MSC growth rate scatter and distribution of fatigue life were in general accordance with experiments. The general approach presented in this Dissertation can be used to advance integrated computational materials engineering (ICME) by predicting variation of fatigue resistance and minimum life as a function of heat treatment/microstructure and surface treatments for a given alloy system and providing support for design of materials for enhanced fatigue resistance. In addition, this framework can reduce the number of experiments required to support modification of material to enhance fatigue resistance, which can lead to accelerated insertion (from design conception to production parts) of new or improved materials for specific design applications. Elements of the framework being advanced in this research can be applied to any engineering alloy.