The flash allowance and upset allowance have significant effects on characteristics of flash butt welded RS590CL steel joints. The overheated zone (OZ) widths increased with flash allowance (δf) increase, and decreased as the upset allowance (δu) increased. The coarsened upper bainite was formed in interface zone (IZ) and OZ as δf increased. With increasing δu, the large plastic deformation occurred and the interface formability improved. The hardness in IZ was a little lower than that in its vicinity OZ due to some ferrite existence and dislocation amount decreased in IZ. The tensile strengths of flash butt welding (FBW) joints were in good match with base metal and the ductilities were lower. The maximum bending crack length was 0.68 mm which indicated that the bending properties of FBW joints were good. Under this experiment, relatively large δf (10–12 mm) and δu (5.5–6.5 mm) were recommended for the benefit of high quality FBW joints.

The gradient cemented carbonitrides with brittle cubic phases containing Ti removed in the surface layers were prepared in this paper. The microstructure, composition distribution, fracture morphology, and transverse rupture strength of these materials were investigated systematically. It is found that the difference between the maximum and the nominal cobalt content augments in the gradient layer, the lattice parameter of (Ti,W)C rises in the bulk inside the gradient border, and the (Ti,W)C cubic phases are refined in the inner bulk as the nitrogen is increased. Besides, the area fraction of WC in the gradient layer is higher than in the bulk, but it decreases remarkably close to the gradient border. The improvement of transverse rupture strength stability depends on thickening of gradient layers, and additionally the transgranular fracture of (Ti, W)C cubic phase can be hardly found in the gradient layer.

Direct coagulation casting of alumina via controlled release of high valence counter ions using ammonium polyphosphate (APP) chelate complex as the coagulating agent was proposed. APP chelate complex suspension was prepared from APP and calcium chloride. Calcium used as high valence counter ions was chelated by APP. The average particle size of the chelate complex is 0.13 μm with a narrow particle size distribution which is close to the size of alumina particles. Glycerol diacetate was used to tailor the pH value of the suspension by hydrolysis which produces acetic acid. The lowering of the pH value helps to decompose the chelate complex, and enhance to release the calcium chelated. It is indicated that the viscosity of the suspensions with the addition of APP chelate complex suspension and glycerol diacetate increases to approximately 20 Pa s after heating at 40–70 °C for 1.5–5 h, which is high enough to coagulate the suspension. 55 vol% alumina suspension with a addition of 3 vol% APP chelate complex suspension and 5 vol% glycerol diacetate treated at 60 °C could coagulate completely within 2 h with a compressive strength of 2.1 MPa. Dense alumina with a relative density of above 97% and a flexural strength of 388 ± 23 MPa can be prepared by this method from 55 vol% alumina suspensions without a burnout process.

Graphene is a 2D carbon allotrope that has attracted significant attention because its properties have a wide range of applications. Graphene was deposited on the polycrystalline nickel substrate with a dimension of 0.10 mm × 10 mm × 10 mm via thermal chemical vapor deposition (TCVD). The natural carbon source was obtained from a commercial palm oil as a carbon precursor. The D, G, and 2D bands described the vibration of graphitic layer and overtone of the D band at 1352, 1594, and 2716 cm−1, respectively. The lowest G band full width at half maximum (FWHM) was 38.7 cm−1 at 900 °C deposition temperature. In the x-ray diffraction (XRD) pattern, the FWHM of Ni (200) peak was 0.38°. Raman spectroscopy, UV–vis spectrophotometry, atomic force microscopy, XRD, and field emission scanning electron microscopy characterized the synthesized graphene. Multilayer graphene was successfully synthesized from the palm oil via TCVD.

This study investigates the ternary intermetallic phases in the Mg–Zn–Ca system, which is of great interest for metallic biodegradable implant applications. According to published phase diagrams, the key alloy composition studied herein is located within the Ca2Mg5Zn5, Ca2Mg6Zn3, and IM1 phase fields. Through controlled cooling of the melt, a quasibinary ∼Ca2Mg5Zn5–Mg microstructure was obtained. The large polygonal grains had a composition of Ca2Mg5Zn5 as determined by energy-dispersive x-ray spectroscopy (EDX). Differential scanning calorimetry revealed that Ca2Mg5Zn5 begins to form at ∼417 °C, and the eutectic temperature is ∼369 °C. Based on single-crystal x-ray diffraction data, Ca2Mg5Zn5 was determined to be hexagonal (P63/mmc), with lattice parameters of a = 9.5949(3) Å and c = 10.0344(3) Å. This was also verified by transmission electron microscopy. Further refinements, which considered the possibility of mixed Mg/Zn sites, significantly improved the data fit compared to the initial ordered structural model. The final refined structure possesses a composition of Ca16Mg42Zn42, very similar to the chemical analysis results from EDX.

Herein, we present a method for decorating multi-walled carbon nanotubes (MWCNTs) with gold nanoparticles (AuNPs) using ethylenediamine (en) as a linker between MWCNTs and AuNPs. The amine group in en is as growth points for synthesis of AuNPs through electrostatic attraction between the amine groups and ${\rm{AuCl}}_4^ -$ anion while sodium citrate act as reducing agent. The influence of HAuCl4 concentration on the size and distribution of AuNPs in the structure of the Au-decorated nanotubes were investigated. Morphology of the decorated nanotubes was characterized by field emission scanning electron microscopy and transmission electron microscopy while the elemental composition of the decorated tubes and crystallography were investigated by energy dispersive x-ray, x-ray diffraction, Raman spectroscopy, and Fourier transform infrared techniques. Cyclic voltammetric and electrochemical impedance spectroscopic analysis revealed that the Au-decorated nanotubes have increased the electro-active surface area and conductivity of electrochemical substrate.

The hot deformation behavior of as-cast AZ91 magnesium alloy reinforced by SiC nanoparticles (SiCp/AZ91 nanocomposite) was investigated using hot compression test. Compared with unreinforced AZ91 alloy, peak stress of the SiCp/AZ91 nanocomposite achieved faster and high temperature deformation ability which was enhanced by the addition of SiC nanoparticles. The values of n for the AZ91 alloy and nanocomposite were 6.9 and 4.6, while the values of Q were 207.96 kJ/mol and 184.6 kJ/mol, respectively. The processing map showed the optimum processing conditions for the nanocomposite mainly concentrated at 523–673 K/0.018–0.001 s−1 and the maximum power dissipation efficiency was found to be 36% at a temperature of 673 K and the strain rate of 0.001 s−1. Based on the constitutive equation and processing map, the deformation mechanism for the present nanocomposite should be dominated by the mechanism of dynamic recrystalization.

An instrumented indentation method is developed for generating maps of time-dependent viscoelastic and time-independent plastic properties of polymeric materials. The method is based on a pyramidal indentation model consisting of two quadratic viscoelastic Kelvin-like elements and a quadratic plastic element in series. Closed-form solutions for indentation displacement under constant load and constant loading-rate are developed and used to determine and validate material properties. Model parameters are determined by point measurements on common monolithic polymers. Mapping is demonstrated on an epoxy-ceramic interface and on two composite materials consisting of epoxy matrices containing multiwall carbon nanotubes. A fast viscoelastic deformation process in the epoxy was unaffected by the inclusion of the nanotubes, whereas a slow viscoelastic process was significantly impeded, as was the plastic deformation. Mapping revealed considerable spatial heterogeneity in the slow viscoelastic and plastic responses in the composites, particularly in the material with a greater fraction of nanotubes.

Thermomigration (TM) and electromigration (EM) are two persistent reliability issues and they generally appear concurrently in solder joints. Many previous studies have attempted to understand the fundamental principles behind these phenomena with the majority of which focusing their interest into the faster migration elements in solders like Bi, Ni, or Cu. However, Sn as the slower migration element has not received that much attention. In the present study, a special linearly symmetrical structure was used. An unusual TM phenomenon of Sn atoms in the Sn58Bi solder joint was observed. The unusual TM of Sn atoms along the vertical edges was attributed to the coupled effect of the EM in the horizontal direction and the TM in vertical direction. The relationships between the microstructural characteristics and the temperature distribution were established. The results also indicated that elevated temperature and sufficient thermal gradient were the two major factors that caused TM.

In this paper, Fe–B amorphous submicrometer particles with a size of 180 nm were synthesized by liquid phase reduction method. The as-synthesized Fe–B amorphous submicrometer particles were annealed at 400, 500, and 600 °C, respectively. The effect of annealing temperature on structure, magnetic properties, and microwave absorption properties of Fe–B submicrometer particles was investigated. Results show that the as-synthesized Fe–B amorphous submicrometer particles were crystallized into Fe2B phase when the annealing temperature was 479 °C. The microwave absorption properties of Fe–B submicrometer particles were dependent on annealing temperature, the paraffin composites containing 60 wt% Fe–B submicrometer particles annealed at 500 °C showed a minimal reflection loss (RL) as low as −43.16 dB at 3.12 GHz with a thickness of 5.1 mm, and the effective microwave absorption (RL < −20 dB) was obtained in a wide frequency range of 2.28–10.48 GHz by adjusting the thickness from 1.8 to 6 mm, indicating excellent electromagnetic absorption properties.

There has been a continuous call for active, durable, and low-cost catalysts for a range of catalysis reactions. In this paper, porous Co@C composed of uniformly dispersed Co metal nanoparticles in hexagonal-shaped prisms carbon matrix were fabricated by in situ pyrolysis of hexagonal-shaped prismatic Co-MOF-74 crystals. The obtained nanoporous carbons have a high surface area of 195.2 m2/g and a strong magnetic response, thereby realizing fast molecular diffusion of reactant and easy magnetic separation. The resulting Co@C catalyst show a superior and durable catalytic activity for reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Moreover, Co@C can be recycled and still retains more than 75% of its original catalytic activity after 6 cycles. Therefore, it is reasonable to believe that such Co@C nanocomposites have great potential as a highly efficient and low-cost heterogeneous catalyst. It is believed that MOFs can be used to produce other catalysts with high porosity and uniformly dispersed active sites.

SrZrO3 ceramic with perovskite-type structure was synthesized by a conventional solid-state reaction method at 1500 °C for 3 h. The crystal structures were studied by x-ray diffraction (XRD), and lattice vibrational modes were obtained by Raman and Fourier transform far-infrared (FTIR) reflection spectroscopy. The dielectric properties of the samples were also measured. According to XRD data, the SrZrO3 ceramic displayed the orthorhombic structure Pbnm (62). The Raman spectrum with ten active vibrators can be fitted by the Lorentzian function, and the vibrators were assigned. Far-infrared spectrum with six infrared active modes was fitted by the four-parameter semiquantum models. Consequently, the modes were assigned as F1u (1) (102 cm−1), F2u (2) (120 cm−1), F1u (3) (140 cm−1), F3u (4)′ (228 cm−1), F3u (4)″ (287 cm−1), F1u (5) (326 cm−1), and F1u (6) (527 cm−1). The infrared mode F1u (1), that can be represented as the Sr–ZrO6 inverted translational vibration, has the highest contribution to the dielectric properties (permittivity and dielectric loss). The calculated data agree well with the measured values.

Cross-weld hardness profile, notch-tensile strength, and impact toughness of T92 steel heat-affected zone (T92 HAZ) of dissimilar T92/TP316H welds were studied in dependence of their postweld heat treatment (PWHT) and subsequent long-term aging. Two weldments series were individually subjected to either “single-step” tempering PWHT or a modified “two-step” renormalizing and tempering PWHT. Subsequently, the welds were isothermally aged at 625 °C for durations from 500 up to 11,000 h. The “single-step” PWHT preserved sharp hardness gradient of T92 HAZ, whereas the “two-step” PWHT led to the hardness values equalization. The T92 HAZ of the weldment after the “two-step” PWHT exhibited initially lower strength and higher toughness, compared to the weldment after the “single-step” PWHT. However, after long-term aging a more suitable combination of T92 HAZ mechanical properties i.e., the higher toughness and acceptable strength exhibited the weldments processed by “single-step” PWHT.

The tin–bismuth eutectic alloy possesses anomalous physicochemical properties that are dependent on temperature. This paper reports the interfacial reaction and growth behavior of the intermetallic compound (IMC) layer during the dissolution of solid copper in liquid eutectic tin–bismuth at 673–823 K under the influence of the structural transition of liquid eutectic tin–bismuth. The structural transition markedly affected the dissolution rate constant of solid copper and the growth rate of the IMCs. Correspondingly, the application of the liquid structural transition significantly decreased the activation energy of dissolution and increased the apparent activation energy for IMC growth. Moreover, two major roles of elemental Bi on the formation and growth of the IMCs were suggested.

Cryomilling combined with laser induction hybrid cladding (LIHC) was adopted to produce NiCrAlY coatings on Ni-based superalloy. The characteristics, oxidation resistance, and mechanical properties of the cryomilled NiCrAlY coatings by LIHC were investigated. By increasing the cryomilling time, the as-received spherical powder experienced a transition from flake-shaped to polygonal structure. The particle size increased firstly and then decreased. Moreover, increasing the cryomilling time induced the columnar growth in the NiCrAlY coatings. This in turn improved the oxidation resistance and the mechanical properties of the coatings. Especially, when the cryomilling time was increased to 15 h, the oxidation resistance of the coating at 1423 K was approximately nine times than that of GH4169 superalloy. The tensile strength of the cryomilled (15 h) coating increased to 1085 MPa and the ductility was 20.7%.

The effects of carbon equivalent on thermal and mechanical properties of compacted graphite cast irons were investigated at ambient temperature, 300 and 500 °C, respectively. The group implied the change of carbon content to control the carbon equivalent. The results indicated that with the increasing carbon equivalent from 4.43 to 4.74, the graphite count increase. The thermal conductivity was 48.64, 44.55, 49.04, and 50.36 W/mK for carbon equivalent about 4.43–4.74 of compacted graphite cast irons at ambient temperature, respectively. With an increase in temperature, the thermal conductivity decrease. Moreover, with the increasing carbon equivalent, the tensile strength and yield strength increase initially, and then decrease at ambient temperature, 300 and 500 °C, respectively. With an increase in temperature, the tensile strength and yield strength decrease. Characterization of fracture surface indicated that the mixed ductile-brittle fracture mode prevailed in the compacted graphite cast irons with different carbon equivalents.

Thick coatings of tetrahedral amorphous carbon (ta-C) have great existing and potential commercial importance for components such as automobile accessories. We confirmed the feasibility of depositing thick ta-C coating on Si wafer, WC, stainless steel (STS), and Al alloy substrates by a home-made filtered cathode vacuum arc. A ta-C coating of 800 nm thickness was successfully deposited over 20 min continuous coating. Interestingly, coatings with thicknesses exceeding 1 μm were easily delaminated by thermal and internal stress effects when the coating time exceeded 20 min. Varying the bias (0 V ↔ 500 V) was highly effective in controlling the internal stress relaxation of the ta-C. This method showed significant improvements in the stress relaxation of the ta-C coatings. By applying multicycle coating, the thickness and hardness of the ta-C coating could reach 9.3 μm and 45 GPa, respectively, at a coating speed of 3.0 μm/h on a fixed substrate.

The effects of Cu content on the microstructure, mechanical property, and hot tearing susceptibility of die casting Al–22Si–0.4Mg alloy have been investigated. Different Cu contents (1.5, 2.5, 3.5, 4.5 wt%) were added in Al–22Si–0.4Mg alloy. In the as-cast microstructure, the amount, volume fraction, and average size of Al2Cu phase increase with more Cu addition. The morphology of grain boundary white Al2Cu phase turns from particle to lump. The UTS (ultimate tensile strength) of Al–22Si–xCu–0.4Mg alloy improves with Cu added, which is mainly caused by the strengthening effect of intergranular Al2Cu. The hot tearing susceptibility apparently rises with Cu content increased, which is due to longer quaternary eutectic reaction time, larger amount of residual intergranular Cu-rich liquid film spreading out over α-Al grain boundary, and higher quaternary eutectic reaction temperature. Considering both the mechanical property and hot tearing susceptibility, optimal Cu content for die casting Al–22Si–0.4Mg alloy found in this paper is 2.5 wt%.