The irradiation damage behaviors of single crystal (SC), coarse-grained (CG), and nanograined (NG) copper (Cu) films were investigated under Helium (He) ion implantation at 450 °C with different ion fluences. In irradiated SC films, plenty of cavities are nucleated, and some of them preferentially formed on growth defects or dislocation lines. In the irradiated CG Cu, cavities formed both in grain interior and along grain boundaries; obvious void-denuded zones can be identified near grain boundaries. In contrast, irradiation-induced cavities in NG Cu were observed mainly gathering along grain boundaries with much less cavities in the grain interiors. The grains in irradiated NG Cu are significantly coarsened. The number density and average radius of cavities in NG Cu was smaller than that in irradiated SC Cu and CG Cu. These experiments indicate that grain boundaries are efficient sinks for irradiation-induced vacancies and highlight the important role of reducing grain size in suppressing radiation-induced void swelling.

The continuation of Moore's law requires new materials at both extremes of the dielectric permittivity spectrum and an increased understanding of the fundamental mechanisms limiting their electrical reliability. To address the latter, reflection electron energy loss spectroscopy has been utilized to measure the band gap of various oxide-based low and high dielectric constant (k) materials of interest to the semiconductor industry. In situ Ar+ sputtering has been additionally utilized to simulate process-induced defect states that are believed to contribute to electrical leakage, time-dependent dielectric breakdown, charge trapping, and other fixed-charge reliability issues in nano-electronic devices. It is observed that Ar+ sputtering predominantly generates surface oxygen vacancy defects in the upper portion of the band gap for both low and high-k dielectric materials. These results are in agreement with numerous theoretical investigations of defects in low and high-k dielectric materials and models for mechanisms that limit their reliability.

The nanoindentation fracture behavior of gallium arsenide (GaAs) is examined from two perspectives in two parent papers. The first paper (part I) focuses on in situ nanoindentation within a scanning electron microscope (SEM) and on fractographic observations of cleaved cross-sections of indented regions to investigate the crack field under various indenter geometries. In the second parent paper (part II), cathodoluminescence and transmission electron microscopy are used to investigate the relationship between dislocation and crack fields. The combination of instrumented in situ scanning electron microscopy nanoindentations and cleavage cross-sectioning allows us to establish a detailed map of cracking in the indented region and cracking kinetics for conical and wedge indenter shapes. For wedge nanoindentations, the evolution of the half-penny crack size with the indentation load is interpreted using a simple linear elastic fracture model based on weight functions. Fracture toughness estimates obtained by this technique fall within the range of usual values quoted for GaAs.

The nanoindentation fracture behavior of gallium arsenide (GaAs) is examined from two perspectives in two parent papers. In the first paper (part I), we address the morphology of the crack field induced by different types of indenters by means of in situ nanoindentation inside a scanning electron microscope (SEM) and of cleavage cross-sectioning techniques. In the present paper (part II), we investigate the early stage of crack nucleation under wedge nanoindentation through cathodoluminescence and transmission electron microscopy. We find that the apex angle of the wedge indenter influences the dislocation microstructure and, as a consequence, the mechanism of crack nucleation under nanoindentation. The formation of microtwins depends on both the orientation of the indenter with respect to the orientation of the GaAs crystal and on the apex angle of the indenter. For dicing applications of GaAs wafers, it is desirable to have an opening angle of the indenter smaller than 70° to facilitate the formation of precursor cracks.

The effect of a strong magnetic field on the solid solubility and the microsegregation during directional solidification of Al–Cu alloy at lower growth speeds (1–10 μm/s) has been investigated experimentally. Results indicate that the magnetic field causes the reduction of the grain boundary and promotes the amalgamation of the grains. Further, measurement results reveal that the magnetic field increases the solid solubility and decreases the microsegregation. It is also found that the value of the solid solubility increases as the magnetic field and the temperature gradient increase. The modification of the solid solubility and the microsegregation under the magnetic field is attributed to the thermoelectric magnetic force acting on the solid and the interdendritic thermoelectric magnetic convection. The present work may initiate a new method to enhance the solid solubility and to eliminate the microsegregation in Al-based alloys via an applied strong magnetic field during directional solidification.

Pure platinum was probed with a nanoindenter fitted with a Berkovich tip to various depths. The indent pattern was made on the as-polished specimen prior to heat treating, after heat treating at 500 °C for 30 min, and again after further heat treating at 1000 °C for 30 min. The variability in the measured hardness decreased as the indentation depth increased from 50 to 300 nm. When the sampled was annealed, the hardness variation was also greater. Increasing hardness variation with decreasing dislocation density and sampling volume indicates that dislocation density plays a critical role in the observed variation, beyond solely instrumentation uncertainty, and supports a defect-based explanation for the stochastic behavior. It appears that the stochastic behavior occurs when multiple dislocations are present in the sampled volume rather than sampling only a single dislocation.

Dynamic recrystallization (DRX) of 99.9999% aluminum single crystal at room temperature was examined under frictionless deformation mode. To exclude the self-heating of the specimen due to applied high strain, a microcrack that localizes the stress at a very small region was intentionally introduced by controlled local necking. For the in situ observation of DRX, a specially designed in situ microdeformation device was positioned inside an electron backscattered diffraction system chamber. Recrystallized grains showed relatively random texture and preferred growth direction. The subgrains with low-angle grain boundaries formed by dynamic recovery transformed into small grains with high-angle grain boundaries, acting as nuclei for discontinuous dynamic recrystallization and growing by further deformation. The DRX in pure aluminum can take place under frictionless tensile deformation conditions at room temperature, and the stress localization and high purity are key issues for the DRX of aluminum at room temperature.

The advanced quenching and partitioning (Q&P) heat treatment has been applied to 9Cr–1.8W–0.3Mo heat resistant steel. The phase transformation during Q&P is measured by a high-resolution differential dilatometer by which the accurate information can be obtained. The transmission electron microscope examination was conducted to study the microstructure evolution after Q&P, and the refined carbon-enriched martensite laths, which were produced during the second martensitic transformation, were observed. The thermodynamics of carbon partitioning was described by a paraequilibrium model according to which the partitioning of carbon from martensite into austenite can be proved. A kinetic model for the second martensitic transformation was developed with the parameters discussed in details. The retardation of onset and end temperature of the second martensitic transformation can be ascribed to the austenite stabilization caused by carbon enrichment.

Using a combination of high-resolution dilatometric measurements and microstructural analysis, this study investigated the bainitic transformation behavior in ultra-high strength 30CrNi3MoV steel after experiencing small deformation at 850 °C (in the nonrecrystallization austenite region). Under the influence of the small deformation in the nonrecrystallization austenite region, the bainite starting temperature (Bs) raised, the bainite finishing temperature (Bf) decreased, granular bainite was promoted to form, and intersections of differently oriented bainite laths became more common in the microstructure. The increase of Bs is owing to the stored energy in distorted austenite grain boundaries, which can serve as an extra mechanical driving force for bainitic transformation during continual cooling. The decrease of Bf can attributed to the more universal intersections of bainite laths with different orientations, which can decelerate the overall growth rate of bainite. The promoted formation of granular bainite is closely related to the increase of Bs because granular bainite usually forms at relatively high temperatures in the bainite range, above upper bainite and lower bainite.

Properties of entangled materials, made of fibers, depend on the number and the nature of contacts between fibers and fibers orientation. Nonsintered and sintered steel wools have been characterized by x-ray tomography to extract structural information such as fibers orientation and number of contacts before and during compression. Image analysis techniques were developed on tomography images and validated on virtual materials, generated and deformed by numerical simulation based on molecular dynamic equations. The structural parameters measured during the structural characterization were finally used to link the structure of the studied material with the measured mechanical properties. To do this link, an analytical model usually used for this kind of material was modified to describe the evolution of mechanical properties in compression.

Decoupled growth often occurs in the nonfacetted–facetted eutectic systems. And it is generally considered that the nonfacetted solid solution acts as the leading phase in the decoupled growth. In this work, Fe40Ni40P14B6 eutectic alloys were systematically studied via solidification of undercooled melts and crystallization of amorphous alloys. Upon solidification of melts subjected to different undercoolings, as the undercooling increases, the growth mechanism develops from cooperative growth to decoupled growth. Upon crystallization of amorphous alloys, the partially crystallized sample consists only of strongly faulted intermetallic (Fe,Ni)3(P,B) with chemical composition deviating from stoichiometry. Formation of supersaturated solid solution γ(Fe, Ni) in the solidification and supersaturated intermetallic (Fe,Ni)3(P,B) in the amorphous crystallization indicates that decoupled growth results from solute trapping and disorder trapping in rapid growth of solid solution and intermetallic, respectively. Further application of rapidly quenched experiments and theoretical analysis declare that the decoupled growth results from a competition between the growth of γ(Fe, Ni) and (Fe,Ni)3(P,B), which are controlled by solute trapping and disorder trapping, respectively.

Suction casting (SC) and centrifugal casting (CC) are two common special casting processes. The influences of SC and CC on the microstructural development of Cu–10Al–4Fe–4Ni aluminum bronzes were investigated with continuous cooling method. The results indicate that α, β′, KII, and KIII phases are observed in the quasicast microstructure via the SC process with the precipitation sequence of KII → α → KIII. Additionally, KI and KIV are observed in the quasicast microstructure via the CC process with the precipitation sequence of α + KⅠ → KII → KIV → KIII. Phase initial precipitation temperatures of the CC process are higher than that of the SC process, especially for α phase. As the quenching temperature decreases, the hardness of both alloys shows a rapid decline trend and finally reaches a steady state. It is found that the eutectoid decomposition (β → α + KIII) barely affects the hardness of the alloys.

A novel kind of solid amine-containing fibrous adsorbent (PP-GMA-TETA) was prepared through irradiation grafting copolymerization with glycidyl methacrylate (GMA) onto polypropylene (PP) fiber, followed by reacting with triethylenetetramine (TETA) to introduce primary and secondary amine groups on its surface. The effects of the reaction conditions, such as the TETA concentration, temperature, and reaction time on amination degree of PP-GMA-TETA, were investigated. Adsorption capacity of PP-GMA-TETA with 77.7% amination degree could reach 4.72 mmol/g. After adsorption, the spent fiber could be completely regenerated at 100 °C by steam for 20 min and its adsorption behavior kept almost constant within six recycles. The comparison of adsorption capacities of amine fibers aminated with various aminating agents also demonstrated that fibers with higher content of primary amine would obtain faster adsorption rates and higher adsorption capacities.

A highly biocompatible peptide, triplet repeats of asparagine–serine–serine (3NSS) regulates mineral deposition for the reconstruction of erosive enamel. Healthy human enamel was demineralized to create lesions, then exposed to the 3NSS peptide solution, and finally immersed in artificial saliva. The degrees of nanohardness recovery were 5.02% and 16.27% for the control group and enamel treated with the 3NSS peptide, respectively. Peptides assembling at enamel interrod attracted greater quantities of ions from the solution to form nanocrystalline hydroxyapatite minerals during the reconstruction of vacant gap. This resulted in a decrease in the surface roughness, and the acidic eroded pores were filled completely. Additionally, the newly deposited hydroxyapatites remineralized with the aid of the 3NSS peptide exhibited a smaller average crystalline size, which effectively inhibited plastic deformations. Treatment with the 3NSS peptide provided great improvements in nanohardness and elastic modulus.

The conventional process for preparing dry spinnable regenerated silk fibroin (RSF) aqueous solution needs not only an addition of Ca2+ but also an adjustment of pH value. In this work, an RSF dry spinning dope was prepared by using a simplified method with solely adding Ca2+. Compared with the conventional RSF solution, the simply prepared aqueous solution showed similar content of β-sheet conformation and diameter of RSF aggregates but lower viscosity. Furthermore, the posttreated RSF fiber dry-spun from this simply prepared solution showed higher crystallinity and crystalline orientation, smaller crystallite size, and better mechanical properties. It could be concluded that Ca2+ played a much more important role than pH value in improving the structures and properties of RSF spinning solution and fibers. Therefore, the step of adjusting pH value could be excluded in the process of preparing high performance RSF fibers.

The objective of this work is to reveal the relationship between the molecular structure and shape-memory property of a hydro-epoxy resin system. The system is prepared using hydro-epoxy, menthane diamine (MDA), and poly(propylene glycol) diglycidyl ether (PPGDGE) with different molecular weights. By keeping the PPGDGE content constant, the crosslink density of the shape-memory hydro-epoxy resin system can be changed by varying the molecular weight of PPGDGE. The results indicate that the glass transition temperature (Tg) and rubber modulus (Er) decrease as the crosslink density decreases. The crosslink density has little influence on shape recovery ratio (Rr). Full recovery can be observed after only several minutes when the temperature is equal to or above Tg. However, the crosslink density has a profound effect on the shape fixity ratio (Rf). If the crosslink density is too low, the shape fixity ratio of shape-memory hydro-epoxy resin would not reach 100%.