In this research, the effect of austenitizing at 900–1100 °C and tempering at 250–650 °C on the microstructure and mechanical properties of 410 and 410 Ni martensitic stainless steels was investigated. The transformation of austenite to ferrite surrounded the austenitizing within the temperature range of 900–1050 °C. The grain size and hardness measurements proved that austenitizing at 1050 °C leads to the partial dissolution of carbides without a considerable growth of austenite grains. The mechanical tests showed two peaks in strength and troughs in ductility by tempering at 450 and 650 °C due to the formation of primary and secondary carbides. The better ductility and fracture toughness in 410 Ni, comparing to 410, were attributed to the effect of Ni on stacking fault energy. Fractured surfaces revealed ductile fracture of the samples tempered at low temperatures, e.g., 250 °C. However, after tempering at 450 and 650 °C, 410 showed a brittle fracture and 410 Ni exhibited a dual intergranular-brittle fracture mechanism.

The effects of retrogression and re-aging (RRA) treatment on intergranular corrosion (IGC), exfoliation corrosion (EXCO), stress corrosion cracking (SCC) behavior and microstructure of spray formed Al-7075 were investigated by a scanning electron microscope, a transmission electron microscope, slow strain rate test, and EXCO and IGC test. The results show that the precipitates are redissolved in the matrix of the alloy after retrogression at 200 °C for a suitable time (8 min), and the grain boundary precipitates are discrete and the obvious precipitate free zones are left at the grain boundaries. After RRA with suitable retrogressed time, thin homogeneous dispersive precipitates are separated out again in the matrix. After retrogression at 200 °C for 8 min and re-aging, the ultimate tensile strength, elongation, IGC depth, EXCO rating, and SCC index of spray formed Al-7075 are 791 MPa, 8.5%, 29.8 μm, EA, and 0.155, respectively.

Aluminum (Al) nanoparticles are synthesized by wire explosion process (WEP) in an inert ambience of argon. Thermodynamic analysis and structural characterization of nano Al particles are made in the present work. Transmission electron microscopy (TEM) characterization has shown that the Al nanoparticles produced are spherical in shape and it follows a lognormal distribution. A unimodal size dependent thermodynamic model is formulated to understand the size dependent thermal behavior of aluminum nanoparticles. Three different melting modes such as, homogeneous melting mode (HMM), liquid skin melting (LSM) and liquid nucleation and growth (LNG) are assumed to understand the melting behavior of aluminum nanoparticles synthesized by the WEP process. The effect of saturation ratio on the nucleation rate and the impingement factor is also discussed. The size dependent melting and enthalpy of fusion of Al nanoparticles predicted by thermodynamic model are in tandem with the DSC results.

The manner in which structure at the mesoscale affects emergent collective dynamics has become the focus of much attention owing, in part, to new insights into how morphology on these spatial scales can be exploited for enhancement and optimization of macroscopic properties. Key to advancements in this area is development of multimodal characterization tools, wherein access to a large parameter space (energy, space, and time) is achieved (ideally) with a single instrument. Here, we describe the study of optomechanical responses of single-crystal Si cantilevers with an ultrafast electron microscope. By conducting structural-dynamics studies in both real and reciprocal space, we are able to visualize MHz vibrational responses from atomic- to micrometer-scale dimensions. With nanosecond selected-area and convergent-beam diffraction, we demonstrate the effects of spatial signal averaging on the isolation and identification of eigenmodes of the cantilever. We find that the reciprocal-space methods reveal eigenmodes mainly below 5 MHz, indicative of the first five vibrational eigenvalues for the cantilever geometry studied here. With nanosecond real-space imaging, however, we are able to visualize local vibrational frequencies exceeding 30 MHz. The heterogeneously-distributed vibrational response is mapped via generation of pixel-by-pixel time-dependent Fourier spectra, which reveal the localized high-frequency modes, whose presence is not detected with parallel-beam diffraction. By correlating the transient response of the three modalities, the oscillation, and dissipation of the optomechanical response can be compared to a linear-elastic model to isolate and identify the spatial three-dimensional dynamics.

Protein cage based nanoarchitectures hold great potential in the fields of energy, catalysis, and bio-applications owing to their ability to tune material’s properties in a benign biomimetic approach. We demonstrate the self-assembly of bacteriophage P22 using inorganic nanoparticles and dendrimers for the first time. Inorganic nanoparticles (iron oxide, CoFe2O4, and Au) and polyamidoamine serve as model systems for rigid and soft linker materials, respectively, to induce P22 assembly via electrostatic interaction. We observed distinctly different packing of P22 using nanoparticles as compared to the polyamidoamine polymer. Notably, the ratio of nanoparticle: P22 and ligand packing on the nanoparticle surface are dominant controls for this assembly. The best results are obtained at 6.5:1 nanoparticle:P22 number ratio in the presence of 50 mM NaCl, pH = 6. In contrast, dense area assembly of P22 is observed at 8:1 polyamidoamine:P22 number ratio with 1 M NaCl (pH ∼ 7.5) for the dendrimer.

Due to the increasingly severe environmental pollution problems, the development of semiconductor photocatalysts is being extensively carried out because they have exhibited high activities for the degradation of many organic and inorganic pollutants. In this study, waxberry-like Ni11(HPO3)8(OH)6 microball photocatalysts with a diameter of 10–20 μm have been successfully synthesized via a solvothermal route by using NiSO4 as a Ni-source and NaH2PO2 as a P-source in a mixture of ethylene glycol and water under the optimized conditions with a Ni:P molar ratio of 1:2 at 200 °C for 16 h. The as-prepared photocatalysts were characterized by powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, Brunauer–Emmett–Teller N2 adsorption, zeta potential, ultraviolet-visible (UV–vis) absorption, and photocatalysis tests. The decolourization of organic dyes, methylene blue and rhodamine B, under ultraviolet light over the as-prepared products reveals an excellent photocatalytic performance due to the good absorption for ultraviolet light.

A theoretical model for the Functionally Graded Shape Memory Alloy (FG-SMA) cylinders subjected to internal pressure is investigated. The gradient properties in this work are embodied in the Young’s modulus and Poisson’s ratio gradient through the thickness of the cylinder. The critical transformation stresses and maximum formation strain are all assumed to be constant. Combining the elasticity and exponential function of the Young’s modulus and Poisson’s ratio with the different gradient parameters, the elastic stress distributions and displacement distributions for the FG-SMA cylinder under the internal pressure are obtained, respectively. To get the theoretical solution, the Tresca yield function and the ideal elastic–plastic constitutive model are selected for the shape memory alloy to illustrate the phase transformation. The relationships between the internal pressure and total strain at the internal radius with different gradient parameters are then given, and the results show that the total strains are greatly influenced by the different parameters.

Cyclic deformation and low-cycle fatigue behavior of Mg–10Gd–3Y–0.5Zr alloy in sand-cast and aging treatment conditions (sand-cast-T6) were investigated by carrying out full reversed strain-controlled tension-compression tests at the strain amplitude ranging from 0.25 to 0.7%. The results show that stress–strain hysteresis loops of the studied alloys display near tension-compression symmetry, which is dominated by microstructure and strain amplitude. Both sand-cast and sand-cast-T6 alloys exhibit cyclic hardening and softening phenomenon with increasing loading cycles. Meanwhile, the fatigue life of the aged alloy is higher than that of the sand-cast alloy at all applied strain amplitudes. The theoretical strain fatigue limits (ε0) of sand-cast and sand-cast-T6 alloys are 2.1% and 2.3%, respectively. In addition, the low-cycle fatigue behavior of the studied alloy at different strain amplitudes was also investigated.

Based on 15 diffusion couples located in face centered cubic single-phase region of ternary Ni–Al–Mo system, high-throughput determination of composition-dependent interdiffusivity matrices at 1273, 1373, and 1473 K was performed by using the recently developed numerical inverse method. The determined main interdiffusivities over the investigated composition and temperature ranges are all positive, and $\tilde D_{{\rm{AlAl}}}^{{\rm{Ni}}}$ is generally larger than $\tilde D_{{\rm{MoMo}}}^{{\rm{Ni}}}$ . Moreover, $\tilde D_{{\rm{AlAl}}}^{{\rm{Ni}}}$ generally increases with concentration of Al, while $\tilde D_{{\rm{MoMo}}}^{{\rm{Ni}}}$ increases with concentrations of both Al and Mo. In contrast, the cross interdiffusivities can be either positive or negative. Average relative errors of $\tilde D_{{\rm{AlAl}}}^{{\rm{Ni}}}$ , $\tilde D_{{\rm{AlMo}}}^{{\rm{Ni}}}$ , $\tilde D_{{\rm{MoAl}}}^{{\rm{Ni}}}$ , and $\tilde D_{{\rm{MoMo}}}^{{\rm{Ni}}}$ were evaluated to be 2.4, 5.1, 16.1, and 1.7% using error propagation. Furthermore, our prediction of composition profiles and interdiffusion fluxes based on evaluated interdiffusivity matrices agrees quite well with measured data. Traditional Matano–Kirkaldy method was also applied to further verify the reliability of obtained interdiffusivities. Besides, three-dimensional planes of activation energies of main interdiffusivities were also evaluated using the Arrhenius equation.

To reveal the electron and phonon transport mechanism in bismuth nanowire (BiNW), the electronic structure, the lattice dynamics, and the thermoelectric properties of bismuth bulk (BiB) and BiNW were investigated in this paper through first-principles calculation and the Boltzmann transport theory. The results suggest that BiNW possesses an increased electrical conductivity and Seebeck coefficient, while its thermal conductivity, especially phonon thermal conductivity, is reduced significantly as compared to BiB. As a consequence, a largely enhanced figure of merit (ZT) at 300 K of 2.73 is achieved for BiNW. The enhancement in electrical conductivity and Seebeck coefficient of BiNW is originated from its high density of states and large effective mass of carriers. Such significant suppression in phonon thermal conductivity of BiNW is ascribed to the reduced phonon vibration frequency, the decreased phonon density of states, and the shortened mean free path of phonons. So BiNW should be viewed as an excellent candidate for a thermoelectric material with a high figure of merit. Moreover, we have provided a complete understanding on the relationship between the electronic structure, the dynamics, and the thermoelectric properties of BiNW.