Microwave irradiation has the potential to affect the mechanical properties of natural silks. We explored several tensile properties of Bombyx mori silkworm cocoon fibers (yield stress and strain, breaking stress and strain, Young's modulus, toughness) as a function of microwave exposure time; samples were stored in a desiccating environment prior to tensile testing. Microwave radiation did not significantly affect any of these properties. We conclude that silk can be incorporated as a reinforcing fiber—without significant deterioration in properties—into materials that are subjected to microwave processing and/or in-service microwave radiation. Microwave exposure decreased the Weibull modulus of fibers, indicating that fracture becomes less predictable as a result of the exposure. Since microwave exposure affects failure predictability but not the average breaking strength of fibers, silk is best suited for use in composite materials if microwave exposure is likely, so that load can be transferred from weaker to stronger fibers.

A low-temperature thin-film processing method for BaTiO3 is studied to understand microstructure development in the presence of a liquid-forming phase. The addition of a eutectic barium borate flux is found to prevent nucleation of BaTiO3 during pulsed-laser deposition on sapphire substrates at 400 °C. Subsequent thermal annealing above the flux's eutectic temperature dramatically enhances the film's microstructural development and crystallinity. A secondary reaction phase of barium aluminate is identified at the substrate interface in both unfluxed and fluxed films, although it is more pronounced in the fluxed films. This barium aluminate phase in conjunction with the liquid flux serves to nucleate {111} twins in the barium titanate, which subsequently lead to enhanced grain growth. The resulting large-grained and dense thin films result in markedly improved dielectric properties.

At room temperature (RT), Fe2Mo3O12 is stable in monoclinic structure phase and above 780 K it transforms to an orthorhombic phase. Experiment shows that in the high temperature orthorhombic phase, the material exhibits low or negative thermal expansion property. In the paper, new compounds with the formula Fe2–x(ZrMg)0.5xMo3O12 (x = 0–1.8) are reported. The compounds are designed and synthesized to reduce the phase transition temperature of the Fe2Mo3O12 by substitutional co-incorporation of Zr4+ and Mg2+ in it. It is found that the monoclinic-to-orthorhombic phase transition temperature can be lowered effectively by the co-incorporation. The orthorhombic phase of Fe0.4(ZrMg)0.8Mo3O12 may be obtained at RT and it may keep the orthorhombic structure as low as 103 K. Meanwhile, the co-incorporation of Zr4+ and Mg2+ may tailor the coefficient of thermal expansion (CTE) of the Fe2Mo3O12 and the near-zero CTEs are obtained for the compound around x = 1.7 (Fe0.3(ZrMg)0.85Mo3O12). This work paves the way toward developing low-cost and near-zero thermal expansion materials over wide temperature ranges.

We present a bottom-up fabrication route to fabricate solid-solution Rh–Pd–Pt ternary alloy nanoparticles (NPs), with well-controlled compositions through femtosecond laser irradiation of a mixed solution of metallic ions, without any reducing agents and complicated processes. The structure of fabricated NPs was crystalline, and formation of solid-solution alloy formation was confirmed by electron and x-ray diffraction measurements. The crystalline nature of alloy NPs was also confirmed through high-resolution transmission electron microscope measurement. According to energy dispersive spectroscopy analysis, elemental composition of an individual NP was almost the same as the initial feeding ratio of ions in the mixed solutions. The electronic state of the element in alloy NPs was confirmed to be pure metal by XPS measurement. The structural studies of Rh–Pd–Pt NPs suggested that the demonstrated technique opens up a new dimension for the fabrication of NPs, which has well-controlled properties for practical use in various fields.

To establish the relationships between composition, microstructure, and properties, the influence of Al addition on microstructure and properties of Cu–Fe-based coatings by laser induction hybrid rapid cladding was studied. With increasing Al content, the main diffraction peaks of ε-Cu phase are weakened but those of α-Fe phase are strengthened, the size of Fe-rich particles generally increases but the dendrite arm spacing is further reduced, and the number of Cu-rich grains precipitated inside the Fe-rich particles increases but the size reduces. Moreover, when the amount of Al is increased, the improvement in electrochemical resistance is attributed to large amounts of fine Cu-rich grains precipitated inside the Fe-rich particles, which results in large anode–small cathode effect. The microhardness also increases with Al content and the microhardness of Cu53.5Fe36Al10C0.5 coating is approximately 2.4 times higher than that of copper alloy substrate.

Morphological evolution and phase transformation of metastable intermediate precipitates are critical to their mechanical properties for the non-isothermal processing. During the non-isothermal precipitation, the formation of the new phases usually couples with structural evolution. Traditional structural characterization has limitation to resolve comprehensive changes simultaneously. In this study, we report direct observation, precipitation sequence, and the details of concurrent morphological and structural changes of various intermediate precipitates during non-isothermal heating in the Al–Cu systems with different pretreatments. The structural heterogeneity during the non-isothermal precipitation processes is resolved into coexistence of two different precipitate phases and quantitatively studied in terms of the phase transition and the morphological evolution. This paper presents the in situ small- and wide-angle synchrotron x-ray scattering (SAXS and WAXS) to refine and to identify the mixed structural information during multiple precipitation stages. The WAXS results show that the precipitation sequence is θ″ → (θ″ + θ′) → θ′ → (θ′ + θ) → θ upon heating. Due to the fact of the specifically oriented SAXS intensity, the evolution of the aforementioned phase transformation is resolved by the refinement of the SAXS intensity integrated over the selected area. These methods reveal multiscale information that is not trivial comparing to the traditional characterization methods.

Heusler Ni–Mn–(Ga, In, Sn, Sb) materials can provide large magnetic-field-induced strain, giant magnetocaloric and magnetoresistance effects based on their first-order solid-state martensitic transformation. In the present work, effects of Co doping on martensitic transformation behavior in melt-spun Ni–Mn–Sn ribbons were studied by x-ray diffraction, scanning/transmission electron microscopy, and thermal analysis. Experimental results showed that both martensitic transition and austenite Curie temperatures increased linearly with Co addition to Ni49Mn39Sn12; and meanwhile, crystal structures of the martensite evolved from four-layered orthorhombic (4O) to five-layered orthorhombic (10M), and then seven-layered monoclinic (14M). The compositional dependence of the martensitic transition temperatures was well correlated with changes of valence electron concentration (e/a) and unit-cell volume of high-temperature austenite. It was proposed that both increase of valence electron concentration and shrinkage of austenite unit-cell volume with Co addition are favorable to the occurrence of martensitic transformation. In addition, the Curie temperature of austenite increases with Co addition, which was ascribed to the enhancement of ferromagnetic exchange interaction.

Various heat treatments and thermal simulation with different austenitizing temperatures and austenite deformation were applied on a bearing steel to obtain various austenitic state. The effect of austenitic state on microstructure of martensite/bainite (M/B) dual phase steel and its mechanical property has been investigated via microstructure observation and kinetic analysis. The results show that the M/B steels austenitized at 900 and 950 °C have better comprehensive performance compared with the steels austenitized at 850 and 1050 °C. The refined microstructure can be obtained after deformation, and the heavy deformation and low deformation temperature are useful for refining the microstructure. The bainite lath is longer and has well-directional arrangement at high austenitizing temperature with the same deformation. Furthermore, austenite deformation can improve the nucleation ratio, reduce incubation process, and affect the kinetics of bainite transformation significantly.

This research discussed how to synthesize submicrometer-sized TiC particulate reinforcement in the molten aluminum melt at low temperature via combustion synthesis by using in situ casting technique. A high temperature preheating treatment of Al–Ti–C pellets was carried out, by which the thermal explosion reaction of the pellets could take place in the pure aluminum melt at 750 °C. The synthesizing temperature of TiC particles was reduced by at least 150 °C compared with the conventional methods. In situ formed TiC particles were spherical in shape and were smaller than 1 µm in size due to the low melting temperature. The emergence of liquid aluminum phase led to the generation and accumulation of plenty of heat in the pellet in a short time due to the reactive diffusion of Al(l)–Ti(s). The formation mechanism of the submicrometer-sized TiC particles in the molten aluminum at low temperature was discussed in this research.

Tribological behavior of biomedical ultrafine-grained (UFGed) TiNbZrTaFe (TNZTF) composites fabricated by powder metallurgy was investigated under dry wear condition. Results show that compared with two kinds of conventional biomedical Ti–6Al–4V (TAV) and Ti–13Nb–13Zr (TNZ) alloys, the wear loss of the TNZTF samples is only 3.5% and 1% of that of the TAV and TNZ samples, respectively. Unusual tribological behavior is that the wear loss of the TNZTF samples decreases with the increase in sliding speed at the same load. This is attributed to the formation of a large amount of hard Nb2O5 particles on the contact surface of the material during rubbing and more severe plastic deformation in the material layers adjacent to the contact surfaces. The wear mechanism of the three kinds of alloys was also investigated. The outstanding tribological property proves that the UFGed TNZTF alloys should be an excellent candidate material to be used for biomedical application in the future.