Grain boundary (GB) segregation can markedly improve the stability of nanostructured alloys, where the fraction of GB sites is inherently large. Here, we explore the concept of entropically supported GB segregation in alloys with a tendency to phase-separate and its role in stabilizing nanostructures therein. These duplex nanocrystalline alloys are notably different, both in a structural and thermodynamic sense, from the previously studied “classical” nanocrystalline alloys, which are solid solutions with GB segregation of solute. Experiments are conducted on the W–Cr system, in which nanoduplex structures are expected. Upon heating ball-milled W–15 at.% Cr up to 950 °C, a nanoscale Cr-rich phase was found along the GBs. These precipitates mostly dissolved into the W-rich grains leaving behind Cr-enriched GBs upon further heating to 1400 °C. The presence of Cr-rich nanoprecipitates and GB segregation of Cr is in line with prediction from our Monte Carlo simulation when GB states are incorporated into the alloy thermodynamics.

Using galvanostatic pulse deposition, we studied the factors influencing the quality of electroformed Bi1–xSbx nanowires with respect to composition, crystallinity, and preferred orientation for high thermoelectric performance. Two nonaqueous baths with different Sb salts were investigated. The Sb salts used played a major role in both crystalline quality and preferred orientations. Nanowire arrays electroformed using an SbI3-based chemistry were polycrystalline with no preferred orientation, whereas arrays electroformed from an SbCl3-based chemistry were strongly crystallographically textured with the desired trigonal orientation for optimal thermoelectric performance. From the SbCl3 bath, the electroformed nanowire arrays were optimized to have nanocompositional uniformity, with a nearly constant composition along the nanowire length. Nanowires harvested from the center of the array had an average composition of Bi0.75Sb0.25. However, the nanowire compositions were slightly enriched in Sb in a small region near the edges of the array, with the composition approaching Bi0.70Sb0.30.

The nanoscale precipitation induced by 1.8 MeV ion irradiation in Cu1−xVx thin films, with x ≈ 0.09 and 0.91, was studied by atom probe tomography. For the Cu91V9 alloys, irradiation in the range of 300–500 °C led to steady-state compositional patterning of V-rich nanoprecipitates. V nanoprecipitates larger than ∼10 nm in diameter, moreover, contained Cu-rich cores, resulting in an unusual “cherry-pit” nanostructure. The number of these pits within one precipitate increased with the precipitate size, but with the volume fraction of pits within a given precipitate remaining roughly constant, from ∼1.5 to 5%. Similar irradiations performed on V91Cu9 also resulted in an enhanced precipitation reaction, but with smaller Cu-rich nanoprecipitates, <3 nm in diameter, and no “cherry pits.” These results are rationalized using recent atomistic simulations that have explored the conditions for stabilizing by ion irradiation “cherry-pit” nanostructures in immiscible A–B alloy systems, such as Cu–V.

The influence of aging treatment on the shape memory effect and corrosion resistance of a newly developed Fe–Mn–Si–Cr–Ni-based alloy containing C, N, and V elements was investigated. Results showed that V(CN) and Cr23C6 particles, precipitated during aging, could improve the shape recovery ratio to 72%, compared with that of 21% for the solution treated sample, when the alloy was aged for 24 h. The corrosion behavior in 0.5 M H2SO4 solution was almost the same for all the samples, barring a slight difference in the passivation range. In addition, the passivation current and critical current required for the onset of passivation of the aged samples were almost triple that of the unaged. In 3.5% NaCl solution the corrosion behavior of all aged samples was that of general dissolution with localized attack (pitting), which can be attributed to the micro-cathodic effect of the V(CN) and Cr23C6 particles precipitated during aging. Although the best corrosion resistance in both H2SO4 and NaCl solutions was shown by the solution treated sample, 24 h-aged sample exhibited an improved corrosion resistance, ascribed to the improved chemical homogeneity of the austenite matrix due to long aging time (24 h).

This article aims to provide a fundamental understanding of the deformation mechanisms of NiTi shape memory alloy (SMA) during the wear process at different temperatures when different microstructures are present. Three temperature regimes were selected namely, T < Mf, As < T < Af, and T > Af, where fully martensitic, martensite co-existing with austenite, and fully austenitic microstructures were formed, respectively. When T < Mf, it was observed that the coefficient of friction had decreased initially and thereafter stabilized at a lower value with increasing wear cycles. More decrease was found when the temperature was near to As. Furthermore, when tested above Af, the coefficient of friction had decreased more significantly under higher load. Difference in the trend of coefficient of friction at different temperatures is originated from the different deformation mechanisms involved in the wear process, particularly the martensite detwinning process, the stress-induced phase transformation process, and the plastic deformation of martensite.

The creep behavior of advanced 9%Cr-1 (BM1) and advanced 9%Cr-2 (BM2) dissimilar welded joints was investigated in this paper, and also the microstructures were elaborately characterized. Based on the fitting with MATLAB, a 3-D curved surface describing the primary and steady-state creep stage was achieved. The comparison of the microstructures of the precreep and aftercreep welded joints shows that δ-ferrite distribution in the heat affected zone (HAZ) of BM2 side plays an important role in determining creep rupture strength. Fracture occurred at the overtempered heat affected zone (OT-HAZ) adjacent to BM2 after creep tests at 538 °C under different stress loads. Microhardness tests revealed that the OT-HAZ adjacent to BM2 has the lowest hardness value compared with the whole welded joint. Numerous creep voids occurring around δ-ferrite, carbides, and grain boundaries were observed on the specimen after creep test. They concentrated and grew up to microcracks, and then induced the fracture at OT-HAZ. Many second phases were also observed in the grain boundary after creep, and the tempered martensite boundaries in the HAZ gradually become obscure as the creep time increases.

The effect of high-energy electropulsing treatment (EPT) on the microstructure evolution, mechanical properties, and fracture behavior of as-treated Ti–6Al–4V alloy strips was investigated. EPT was found to accelerate phase transition and microstructure evolution of quasi-single-phase titanium alloy strips at a relatively low temperature, and obtain characteristic duplex microstructure and Widmanstatten microstructure. The EPT-induced microstructural changes increased elongation-to-failure remarkably with a slight decrease in tensile strength. Fracture surface observation and three-dimensional analysis showed that transition from small-shallow dimple colony to big-deep colony fracture took place with an increase in frequency of EPT. The rapid phase change of the Ti–6Al–4V alloy strip under EPT was attributed to the enhancement of nucleation rate and atomic diffusion resulting from the coupling of the thermal and athermal effects. It is supposed that EPT can provide a highly efficient method for the intermediate-softening annealing of titanium alloy sheet/strips.

A continuous nonflux inclusion-removal method, rotating gas bubble stirring, is used to purify Mg–10Gd–3Y–0.5Zr melt. The effects of rotating gas bubble stirring process parameters (Ar flow rate, time, and rotating speed) on purifying effectiveness, mechanical properties, and fracture behavior of sand-cast Mg–10Gd–3Y–0.5Zr alloy are studied. The results show that too high or too low Ar flow rate is unfavorable for inclusion-removal. The results also indicate that the high rotary speed of spraying gas is helpful to improve the inclusion-removal and mechanical properties. But when the melt is subjected to overtime gas bubbling treatment, the mechanical properties became poor again. Nonflux purification does not change the microstructure of Mg–10Gd–3Y–0.5Zr alloy. However, rotating gas bubble stirring has a certain effect on the fracture pattern of the alloy. In addition, the melt purifying mechanism of the gas bubble stirring treatment for the sand-cast alloy was discussed systematically.

Five well-known Zr-based alloys of the systems Zr–Cu–Al–(Ni–Nb, Ni–Ti, Ag) (Cu = 15.4–36 at.%) with the highest glass-forming ability were comparatively analyzed regarding their pitting corrosion resistance and repassivation ability in a chloride-containing solution. Potentiodynamic polarization measurements were conducted in the neutral 0.01 M Na2SO4 + 0.1 M NaCl electrolyte and local corrosion damages were subsequently investigated with high resolution scanning electron microscopy (HR-SEM) coupled with energy dispersive x-ray spectroscopy (EDX). Both pitting and repassivation potential correlate with the Cu concentration, i.e., those potentials decrease with increasing Cu content. Pit morphology is not composition dependent: while initially hemispherical pits then develop an irregular shape and a porous rim. Corrosion products are rich in Cu, O, and often Cl species. A combination of low Cu and high Nb or Ti contents is most beneficial for a high pitting resistance of Zr-based bulk metallic glasses. The bulk glassy Zr57Cu15.4Al10Ni12.6Nb5 (Vit 106) and Zr52.5Cu17.9Al10Ni14.6Ti5 (Vit 105) alloys exhibit the highest pitting resistance.

We presented the investigation on the cooling rate dependent undercooling of the microsized and nanosized Bi droplets in the Zn matrix via differential fast scanning calorimetry at scanning rates ranging from 300 to 6000 K/s. The experimental results demonstrated that the embedded nanosized Bi droplets gave more reproducible undercooling measurements than that of microsized Bi droplets at the grain boundaries. In addition, different cooling rate dependences of undercooling of microsized and nanosized Bi droplets were found. When the cooling rate is increased from 300 to 6000 K/s, the undercooling of the embedded nanosized Bi droplets increased gradually from 125 to 130 K. However, for microsized Bi droplets at the grain boundaries, there was an obvious increase of undercooling when the cooling rate was higher than 2000 K/s. In other words, the undercooling evolution displayed a sigmoidal relationship with the increase in cooling rate, indicating the change of the heterogeneous nucleation mechanism from a surface-induced mode to a volume-induced one.

The effects of trace La additions on the microstructures and mechanical properties of Cu–0.2 wt% Zr alloy have been investigated. Traditional thermo-mechanical processing was applied to the Cu–Zr alloys. Isochronal aging and isothermal aging were used to optimize the aging conditions. According to the hardness and conductivity tests, the optimized aging condition should be 150 min isothermal holding at 400 °C following 85% cold-rolling. If the as-cast sample is subjected to aging, the addition of La obviously refines the microstructures. After cold-rolling, however, the La addition has no significant effects on the grain size of the aged sample. SEM and TEM are combined to observe the distribution and morphology of the precipitates, which are identified to be Cu5Zr. The addition of La can improve the hardness and conductivity simultaneously in the as-cast samples after aging, while it improves the hardness and strength and decreases the conductivity slightly in the cold-rolled samples after aging. XRD and TEM results show that the lattice parameter and the dislocation density are increased by the addition of La.

The effects of Fe2B-grain orientation on microstructure and properties of bulk Fe2B intermetallic fabricated by directional and ordinary solidification techniques have been investigated. The results show that unidirectional solidified Fe2B intermetallic possesses a strong (002) texture in the transverse direction owing to the opposite unidirectional heat-squeeze effect while random Fe2B grains can be produced under ordinary solidification conditions. The nonoriented Fe2B intermetallic has the highest linear expansion coefficient of 13.04 × 10−6 °C−1 while the microhardness and fracture toughness of transverse Fe2B intermetallic in the (002) plane are larger than those of Fe2B with other grain orientations and their values are ∼18.72 GPa and 6.42 MPa·m1/2, respectively. Liquid zinc corrosion results indicate that unidirectional Fe2B intermetallic with long axis perpendicular to the direction of liquid zinc corrosion displays the best corrosion resistance to liquid zinc owing to its beneficial barrier effect. The FeB transition phase can naturally form and grow parabolically during liquid zinc corrosion.

In this study, a novel hybrid block copolymer containing POSS (BCP), poly(methacrylisobutyl-POSS)-b-poly(methylmethacrylate) (PMAiBuPOSS-b-PMMA) was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The structure and molecular weight were characterized via 1H NMR and GPC. BCP was creatively used as the compatibilizer to overcome the bad compatibility of epoxy and POSS in their blend system. SEM and dynamic mechanical thermal analyses (DMTA) were used to observe the surface morphology and thermal–mechanical behaviors of the resultant products. We found that the amount of microaggregation domains of POSS decreased, while the nano ones increased, when BCP content increased. All the aggregation domains were distributed in epoxy matrix uniformly at nanoscale with the addition of 10 phr BCP and 5 phr POSS monomers. The results indicated that BCP could effectively improve the compatibility between epoxy resin and POSS owing to its amphiphilicity in DGEBA. The fracture behavior of products transformed from brittle fracture to ductile fracture gradually with the increase of BCP, whereas the Tg and E′ decreased.

The magnetization behavior under temperature and magnetic field variation was investigated for La0.7Pb0.3MnO3 ceramics and ferromagnetic–ferroelectric 0.85(La0.7Pb0.3MnO3)–0.15(PbTiO3) composite. The second-order ferromagnetic phase transition in manganite is shifted to the tricritical point in composite material. Comparison of the intensive caloric effect and the difference between relative cooling powers (RCP) in both materials proves a significant role of intrinsic pressure in elevating caloric efficiency in composite induced by elastic coupling between the grains of LPM and PT components. No temperature change in composite under an electric field of 2 kV/cm associated with electrocaloric effect or indirect magnetoelectric coupling was observed. The effect of magnetic field on some peculiar temperatures is considered. A contribution from pressure generated by magnetic field to baric coefficient dT/dp of ferromagnetic transformation temperature in composite was suggested. The results obtained were analyzed in the framework of the magnetic equation of state and compared with the experimentally measured heat capacity.

We have investigated the effects of crystal structure and size of Li[Ni1/3Co1/3Mn1/3]O2 (L333) cathodes on the performance of lithium-ion batteries. Cation ordering and particle sizes were determined as a function of annealing temperature with subsequent electrochemical performance monitored by cyclic voltammetry (CV) and charge–discharge testing. With increasing annealing temperature, L333 exhibits a greater cation ordering, which subsequently benefitted cell performance. However, higher annealing temperatures yielded larger crystal sizes, which resulted in a decrease in high rate discharge capacity and a significant capacity fade. This is attributed to an increase in lattice parameter and volume expansion during cycling, with the largest crystal sizes displaying the most significant structural changes due to the lower strain accommodation.

In the present work, for the first time, the inorganic Si-based materials lacking preexisting mixed bonds (O–Si–C, silicon in tetrahedral coordination bonded to both carbon and oxygen) have been successfully used as starting materials in a laser evaporation/condensation system for making hydrogenated silicon oxycarbide (Si–O–C–H) nanoparticles containing mixed bonds. The obtained materials are characterized by spectroscopic, microscopic, and calorimetric measurements. Thermodynamically stable 5–10 nm amorphous Si–O–C–H particles with a complex structure containing a combination of pure and mixed Si-based tetrahedral units (SiOiC4−i; i = 0–4), and a considerable amount of Si–OH and C–H bonds have been synthesized. The nanoparticles possess high surface areas (428–467 m2/g), suggesting potential use in functionalities requiring high surface to volume ratios. In addition, making thermodynamically stable Si–O–C–H ceramics using a pathway different from the polymer route raises the likelihood of formation of similar carbon containing compounds in the planetary accretion and the Earth's interior.

Using nanoparticulate TiO2 films, the photocatalytic growth of Ag nanoparticles (NPs) in the AgNO3 aqueous solution has been studied in terms of reduction, nucleation, and coalescence. It was proved that Ag primary particles were formed in a growth time of <1 s after the photocatalysis started. The growth dynamics was found to be critical for isotropic and anisotropic growth of Ag NPs, depending on the AgNO3 concentration and surface properties of TiO2 films. In the AgNO3 solutions of ≤300 mg/L, the isotropic growth dominates the growth dynamic behavior, producing irregularly spherical Ag NPs. In the AgNO3 solutions of ≥400 mg/L, the increased reduction rate promotes the formation of Ag nanoplates in the product. Ostwald ripening and oriented attachment were suggested to be the mechanisms dominating the isotropic and anisotropic growth, respectively. A photocatalytic growth model of Ag NPs was proposed by taking Ag atom and Ag+ ion diffusion into consideration. The plasmonic properties of the Ag–TiO2 films were studied in terms of extinction, surface enhanced Raman scattering, and fluorescence enhancement.

Vertically aligned, untangled planarized arrays of multiwall carbon nanotubes (MWNTs) with Ohmic back contacts were grown in nanopore templates on arbitrary substrates. The templates were prepared by sputter depositing Nd-doped Al films onto W-coated substrates, followed by anodization to form an aluminum oxide nanopore array. The W underlayer helps eliminate the aluminum oxide barrier that typically occurs at the nanopore bottoms by instead forming a thin WO3 layer. The WO3 can be selectively etched to enable electrodeposition of Co catalysts with control over the Co site density. This led to control of the site density of MWNTs grown by thermal chemical vapor deposition, with W also serving as a back electrical contact. Ohmic contact to MWNTs was confirmed, even following ultrasonic cutting of the entire array to a uniform height.