Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

We report evidence for graphene layer rearrangements in heavy ion interactions with carbon onions at 140 MeV and 70 MeV per nucleon kinetic energies. Graphene layer rearrangements have been recently predicted in spherical and cylindrical multi-layer graphene systems. The implications of graphene layer rearrangement on the tribological performance of multi-layer nano-carbons in extreme environments are discussed.

Growth orientation and type of internal structures are both observed to change abruptly as a function of growth temperature in catalyst free growth of gallium nitride nanowires. In the present work, corresponding temperature-dependent changes in the growth matrix substrate that can affect the availability of nucleation sites and influence the reactivity of constituent adatom materials in catalyst-free nanowire growth are investigated. The influence of Ga vapor pressure and an abrupt change in the availability of single versus molecular adatom constituents is identified as a possible controlling parameter.

The evolution of carbon onion structure from spherical to polyhedral is correlated with changes in the sp3/sp2 ratio as a function of increasing synthesis temperature using electron energy loss spectroscopy, scanning electron microscopy, and high resolution electron microscopy. Results that are obtained using asymmetric f-variance versus symmetric Gaussian deconvolution of electron energy loss spectra are compared. The possibility of a separate peak at 287 eV is discussed.

Heavy ion irradiations of single and multi walled carbon nanotubes and total ionization dose of gallium nitride nanowires were investigated. Post irradiation analyses of samples were performed with transmission and scanning electron microscopy, atomic force microscopy and micro Raman spectroscopy.

The ABET Engineering Criteria 2000 is stimulating development of quantitative feedback systems in the context of Engineering education. Efforts in developing feedback loops that carry quantitative information to facilitate the improvement of student learning in several engineering majors is summarized. Feedback loops are designed around the course learning objectives that were developed in the context of professional criteria specified by professional societies as well as ABET EC 2000 criteria 2 and 3, which define capabilities that all engineers must gain. Two feedback structures are described – one brings information from external sources such as alumni, employers, and the external advisory board, while the other moves information up and down the pedagogical prerequisite tree. Both loops go through the ABET/curriculum committee for assessment of progress and identification of needed changes. The tool developed to facilitate communication up and down the prerequisite tree is the course evaluation form, on which student and faculty assess students' mastery of the learning objectives. This form is passed through feedback loops that operate on many scales. Progress toward implementation is described, with emphasis on service courses that see student flow between different departments.

Crystallographic structure plays an important role in determining the fundamental physical properties of metallic thin films and superlattices, and structural characterization of such films is crucial for furthering the application of these materials [1]. Epitaxial films are usually characterized using a wide range of techniques including x-ray diffraction, REED, neutron diffraction, and highresolution electron microscopy. A complementary approach is electron backscatter patterns (EBSP), which is an SEM technique that can be used to measure crystallographic orientations of single or polycrystals [2].

In this work, EBSPs have been used to characterize the crystallite size and orientation of sputterdeposited Cu films. The EBSPs were formed in a CamScan 44FE SEM and recorded using an ORTEX CCD camera system. The images were analyzed using the Channel+ software package, and orientation maps were plotted using Channel+Ice [3].

In an effort to understand dislocation mobility in stoichiometric NiAl single crystals, in-situ tensile deformation experiments have been performed in a transmission electron microscope. Commercially pure and high purity single crystals with <001> and <110> orientations have been examined. Two different thermal treatments were adopted in order to effect the mechanical response. Dislocation motion was observed in all samples. Pre-existing dislocations, either isolated or tangled, were not observed to move at any point leading up to sample failure. Cross-slip of the mobile dislocations was observed in some cases. In commercially pure single crystals, dislocations were found to move at a much slower rate and uniform manner in contrast to motion in high purity single crystals which occurs by rapid jumps.

The structure and distribution of dislocations in the region of crack tips and crack edges have been examined in single crystal stoichiometric B2 NiAl using electron channeling contrast imaging (ECCI). ECCI, which allows examination of near surface substructural crystalline defects in bulk specimens, has been carried out for undeformed as well as in-situ deformed 4-point bend specimens. Images of dislocations at crack tips and along the crack fracture surfaces have been studied. Observations have been correlated with variations in thermal treatment corresponding with brittle and toughened conditions. A higher dislocation density was observed over a larger region in front of crack tips for the toughened materials as compared to brittle material.

High-resolution transmission electron microscopy has been used to investigate the structure and growth behavior of three separate multilayer systems composed of spin-glass alloys(AuFe.03,CuMn.15, and AgMn.09) alternating with amorphous silicon. Each of the three systems was fabricated with two different sample configurations. The first consisted of bilayers with 3 nm spinglass alloy and 7 nm amorphous siliconlayers. The second consisted of 7 nm spin-glass alloy and 7 nm amorphous silicon layers. HRTEM images of ion-milled cross-sectioned samples revealed variations in the degree of crystallinity of the spin-glass material. Variations in the amount and symmetry of interlayer formation were also observed. Systematic studies of such variations should help to explain differences in their measured spin-glass properties.

B2 CoAl single crystals with a number of orientations have been deformed at 1300 K and 1000 K. The deformation substructures have been characterized using TEM diffraction contrast techniques supported by image simulations. While <100> slip is found to be the predominant slip mode at these temperatures, <111> and <110> dislocations have also been observed. In particular, in hard orientations <110> dislocations appear to play an active role in initiating the deformation. Additionally, <110> dislocations are often observed as junctions of <100> type dislocations. Under the conditions tested, changes in alloy stoichiometry do not result in any modifications to the dislocation slip behavior.

High resolution electron microscopy has been used to study the core structure of a/2[101] and a/3<112> dislocations in Ni3Al deformed in the range of increasing strength with temperature. a/3<112> coupled SISFs were found to lie on (111) and their structure agreed well with theoretical predictions. a/2[101] superpartials were always dissociated on (111) or (111) planes while the APB plane was found to be (010). Computer simulation of dislocation core structures were found to agree well with the observed dissociations. The APB width was found to increase significantly with increasing deformation temperature near the peak yield strength temperature.

It has been shown that it is possible to obtain significant room temperature tensile ductility in FeAl alloys using iron-rich deviations from stoichiometry. A comparison of the room temperature tensile and compressive behaviors of Fe−50at% Al and Fe−40at% Al shows that FeAl is brittle at higher Al contents because it fractures along grain boundaries before general yielding. Lower aluminium contents reduce the yield stress substantially and hence some ductility is observed before fracture.

Addition of boron results in measurable improvements in ductility of Fe−40at% Al and is accompanied by an increase in transgranular tearing on the fracture surface, suggesting a grain boundary strengthening mechanism.

Increasing the cooling rate following annealing at 1273 K results in a large increase in the yield strength and a corresponding decrease in ductility.