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The development of advanced materials, with complex microstructures, is a permanent challenge to the development and application of new efficient techniques for microstructural characterization. In ceramic coatings on metals, there exist a differential ion-milling ratio between both components, limiting in principle the use of conventional techniques. In this work, we report on a comparative study of TEM sample preparation techniques for plasma-sprayed ceramic coatings. Firstly, we have used a procedure derived from the conventional one (polishing, dimpling, ion milling), and alternatively a new technique using focused ion-beam milling. The material selected for this study is fine-grained alumina that was plasmasprayed on a steel substrate. The efficiency of both techniques is discussed along with the most significant microstructural features of the material subject of study.El desarrollo de materiales avanzados, con microestructuras cada vez más complejas, supone un reto constante de desarrollo y aplicación de técnicas que permitan el análisis de la microestructura de forma eficiente. En el caso de los recubrimientos cerámicos sobre substrato metálico, la diferente velocidad de adelgazamiento iónico que suelen mostrar ambos sistemas supone, en principio, una limitación sustancial. En este trabajo, presentamos un estudio comparativo de la fabricación de láminas delgadas para microscopía electrónica de transmisión, empleando en primer lugar una técnica derivada de la convencional (desbaste, pulido y adelgazamiento iónico), y alternativamente una novedosa técnica de ataque selectivo mediante un haz iónico. El material elegido para realizar este estudio ha sido un recubrimiento de óxido de aluminio de grano fino proyectado por el método de plasma sobre acero. Se discute la eficiencia de cada una de las técnicas, así como las carácteristicas microstructurales más destacadas en el material objeto de estudio.

Examines the role of isovalent dopants in the high-temperature deformation behavior of gallium arsenide. Details of the experimental procedure; Summary of work on both undoped and boron and indium-doped crystals; Results of the solute hardening analysis.

Presents a study which examined the deformation behavior of undoped and indium (In)-doped gallium arsenide (GaAs) single crystals. Measurement of the temperature dependence of undoped and In-doped GaAs; Experimental procedures used; Values for the upper yield as a function of temperature.

Presents a study which measured high-temperature hardness of Ga[sub1-x]In[subx]As. Experimental details; Results and discussion; Conclusion.

Progressive fiber debonding in steel fiber/cementitious matrix composites has been studied using a single fiber pullout test that permits simultaneous measurements of the load versus crack opening displacement relationship and Molt6 interferometry fringe patterns. Analysis of Moir6 interferometry patterns allows the fiber axial and interracial shear stresses to be calculated along the entire fiber length. The interracial shear stress distribution along the debonded length of the fiber indicates a steep decrease in shear stress with interracial slip, from 6 to 1 MPa for 7 [micro]m of fiber slip and a crack opening displacement of 22 [micro]m. These results suggest that improvements in the toughness of cement-based composites could be achieved by developing materials in which the decrease in shear stress is less severe.

A multi-element, time-dependent model developed by Childers et al. [A.S. Childers, M.T. Johnson, J. Ramírez-Rico, and K.T. Faber, J. Electrochem. Soc., 160:3093-3102, 2013] for copper infiltration of large (~50-200 μm diameter), high aspect ratio (~60) through-hole channels was experimentally tested for validity. The model built on the work of Akolkar and Landau [R. Akolkar and U. Landau, J. Electrochem. Soc., 151:702-711, 2004] for copper deposition in micro-scale integrated circuitry. Childers' model broadens the original by including the transport and adsorption of all electrolyte species - inhibitors, accelerators, and copper ions. The resultingmodel is tested experimentally with wood-derived biomorphic carbon materials. Results indicate that model predictions of premature pore choke off are in agreement with quantitative observations of copper infiltration and qualitative imaging of plated pore profiles. Low accelerator concentrations (0.002 ppm) yielded the highest quantity of copper infiltration without premature closure. [ABSTRACT FROM AUTHOR]