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Catastrophic brittle failure of ductile materials by liquid metal embrittlement (LME) is a widely documented phenomenon but the fundamentals of its initiation mechanism are poorly understood. The widespread use of Zn-coated advanced high strength steels in the automotive industry has been plagued by Zn-induced LME which is frequently observed in high-temperature forming and welding applications. In this study, numerical modeling and an atomic-scale experimental investigation are used in order to gain insight into the atomistic events that lead to the onset of LME cracking. The results showed that the formation of a stress-induced diffusion wedge (SIDW) at the exposed grain boundary (GB) due to the interdiffusion of Zn-embrittler atoms was the trigger for LME. The formation of the SIDW facilitated the diffusion of the Zn-embrittler atoms into the GBs, which compromised their mechanical integrity. The results show that LME initiation entails several steps: (i) solid-state GB diffusion, (ii) formation of the SIDW, (iii) eventual melting of the SIDW, and (iv) opening of the liquid wedge due to interdiffusion and the application of externally applied stresses. [ABSTRACT FROM AUTHOR]

The Ti–15Mo alloy has become a widely recognized biomedical Ti alloy due to its excellent properties, including a low Young's modulus that is close to that of a human bone. Selective laser melting (SLM) additive manufacturing (AM) offers both advanced manufacturing capabilities to the processing of the alloy and the potential to make customized implants. The feedstock cost of pre-alloyed Ti–15Mo powder, however, is high, like that of many other Ti alloys, and can be a major obstacle to the wider application of the AM technique. This study focused on mitigating this problem by using an in situ laser alloying approach, wherein a low-cost hydride-dehydrate (HDH) Ti powder was mechanically mixed with elemental Mo powder to form a composite powder feedstock (i.e., Ti + Mo). The Ti–15Mo alloy could be printed with a high relative density (~ 99.76%). A finite element simulation was performed to study the melt pool during the SLM process with subsequent detailed discussions to understand the in situ alloying mechanism. Mechanical property indicates the as-printed Ti–15Mo has high strength (~ 1170 MPa) but low ductility, while the latter has been much improved by introducing a merely 0.2 wt% of yttrium (Y). Based on the optimized Ti–15Mo–0.2Y alloy with a strength of ~ 1300 MPa and a modulus of ~ 85 GPa, different amounts of elemental Ag powder were further alloyed in situ to acquire antibacterial properties. Compared with the antibacterial activity of the control group, that of the final material, i.e., in situ laser alloyed Ti–15Mo–0.2Y–2.5Ag, reached 92–95%; the addition of Ag had a minimal effect on the cell viability. In vivo experiments demonstrated the Ag-containing alloys to exhibit good biocompatibility. [ABSTRACT FROM AUTHOR]

Lath martensitic high-strength steels are some of the most widely used materials in structural applications, and consequently, refining and controlling the lath martensitic morphology is of significant interest to expand the versatility of the steels and their associated range of applications. It is well known that the steel's carbon content has a pronounced effect on the lath martensitic morphology, its crystallography, and hierarchical structure, but the effect of other elements like Mn and Ni is still relatively unclear. This study provides a comprehensive investigation on the effect of Ni on the morphology, crystallography, microstructural refinement, internal transformational strain, and mechanical properties of lath martensite using advanced analytical tools at the meso-, nano-, and atomic scales to offer insights that have so far been lacking in the literature. The in situ alloying of Ni with the bulk microstructure triggered a relatively ideal martensitic transformation such that the majority of the austenite (γ) grains transformed into four martensitic packets (with each packet representing one of the four close-packed {111} planes in a given γ-grain) with a relatively homogenous distribution of the twenty-four martensitic variants that can potentially evolve in an γ-grain based on the Kurdjumov–Sachs (K–S) orientation relationship. The addition of Ni lowered the martensite start (Ms) temperature and strengthened the γ-matrix at lower temperatures, which resulted in the refinement of the packets and blocks due to an inherent need by the matrix to self-accommodate the transformational strain, whereby significantly decreasing the internal strain in the microstructure. The results of this study showed that alloying lath martensitic steels with Ni can prove to be an effective method to refine the hierarchical microstructure in a way that can be used to improve the mechanical properties of these steels. [ABSTRACT FROM AUTHOR]

Tensile behavior at different deformation temperature of a transient liquid-phase (TLP) bonded joint of γ′-strengthened Co-based superalloy was investigated. A temperature dependence phenomenon of the joint's fracture position was found, which transferred from the base metal to the bonding area with increase in the temperature, and this is related to the deformation mechanism. At room temperature, dislocation shearing the γ′ phases in different areas of the joint domains the deformation and makes it heterogeneous, and more deformation has occurred at the BM because of lower content of γ′ phase, which makes the failure occurred at the BM. The deformation mechanism gradually transferred from dislocation shearing to bypassing the γ′ with increasing the temperature, making the deformation become diffused, and this can lead to the fracture of the joint's brittle borides, and the coalescence of the boride-induced cracks makes the fracture occur at the diffusion affect zone at 600 °C~ 900 °C. As the secondary-γ′ in the joint's isothermal solidification zone dissolves at 1000 °C, more deformation occurs there and the accumulation of micro-voids induced by the dislocation climbing leads to the fracture. [ABSTRACT FROM AUTHOR]

Room temperature tensile testing was performed on a coarse-grained polycrystalline Ni (32 μm), a nanocrystalline Ni (23 nm) and two nanocrystalline Ni-Fe (16 nm) electrodeposits at two strain rates of 10 and 10/s. Strain localizations and local temperature increases were simultaneously recorded during tensile testing. For all materials, higher loads or higher strain rate generally resulted in higher peak temperature with the highest temperatures recorded in the fracture regions. The maximum temperature for the nanocrystalline materials was just over 80 °C, which is significantly below the reported temperatures for the onset of thermally activated grain growth. Therefore, the previously reported grain growth observed on similar materials after tensile deformation is likely not thermally activated but a stress-induced phenomenon. Despite the wide grain range from 16 nm to 32 μm, all samples exhibited similar strain localization behavior. Local strain variations initiated in the early stage of macroscopic uniform deformation, subsequent necking and fracture took place in the region of initial strain localization. While the coarse-grained polycrystalline Ni exhibited little strain rate sensitivity, gradually increased strain rate sensitivity was observed for the 23 nm Ni and the two 16 nm Ni-Fe samples, suggesting that both dislocation-mediated and grain-boundary-controlled mechanisms were operative in the deformation of the nanocrystalline Ni and Ni-Fe samples. [ABSTRACT FROM AUTHOR]

To identify the structural role of alloying element M (M = Ti, Ga, Co, Fe) on the glass-forming ability (GFA) of Cu 50Zr 50 base alloy, the atomic structures of the binary and ternary metallic glasses were examined by extended X-ray absorption fine structure (EXAFS) spectroscopy. The EXAFS curve-fitting analysis indicates that the main structural difference among the metallic glasses is in the atomic packing density of Cu-centered clusters. The relative shortening of the Cu–M distance is closely related to the heat of mixing between Cu and M: the more negative the heat of mixing, the larger is the shortening of the Cu–M distance. Based on a systematic analysis of the component properties and GFA data for Cu–Zr based alloys, it is suggested that alloying elements that bring a more uniform distribution of atomic size and possess strong chemical interactions with the main components should be selected in developing large-size bulk metallic glasses. [ABSTRACT FROM AUTHOR]

The bulk specific heat of fully dense nanocrystalline Ni-P electrodeposits with essentially constant P content (about 4 at%) and varying average grain sizes from 6.9 to 28.9 nm was investigated using modulated differential scanning calorimetry. In the lower temperature range from room temperature to 120 °C, at which the as-deposited sample microstructure was thermally stable, the bulk specific heat varied only within ~2 % despite the substantial variation of interface volume fractions from 0.11 to 0.39 for this series of samples. Moreover, the measured bulk specific heat values of the Ni-P samples were all located within the reported specific heat value range for conventional polycrystalline Ni. Evidently, the contribution due to grain size-related interface excess free volume is negligible and the bulk specific heat for the materials can be characterized as a structure-insensitive property. In the elevated temperature range from 150 °C to the Curie temperature of 357 °C, the magnetic contribution to the specific heat was significantly influenced by the chemical environment of P in the Ni-P samples. When P atoms were in the form of supersaturated solution in the nickel matrix, a complete suppression of the characteristic λ peak of the magnetic contribution in the specific heat curves was observed for all materials. The λ peak re-appeared in the specific heat curve after the Ni-P sample underwent a transformation to a two-phase microstructure consisting of Ni and NiP grains. It can be concluded that at a given P content, paramagnetic phosphorus atoms in the form of solutes are more effective in reducing the magnetic contributions to the specific heat than the form of paramagnetic NiP second-phase particles for the nanocrystalline Ni-P alloy. [ABSTRACT FROM AUTHOR]

Low temperature interconnection processes for lead-free packaging and flexible electronics are currently of great interest. Several studies have focused on bonding using silver nanoparticles (Ag NPs) or copper nanoparticles (Cu NPs). However, pressure assistance is generally necessary for bonding with nanomaterial pastes, which limits its industrial applications. Here, a unique method for bonding of copper wires using Ag NP and nanowire binary pastes is examined, in which joining is accomplished from 60 to 200 °C and yet without the application of pressure. Bonding is facilitated by solid state sintering of Ag nanomaterials and metallic bonding between Cu and Ag interfaces. The effects of different additions of Ag nanowires in bonded joints are studied, in which addition of 20 vol% Ag nanowires improves bonding strength after low temperature sintering by 50-80 % compared with Ag nanoparticle paste. A mechanical reinforcement effect due to introduction of Ag nanowires has been confirmed by observation of the fracture path propagation, where necking, breakage and pullout of nanowires occur on loading. This low temperature pressureless bonding technology has the potential for wide use for interconnection in lead-free microcircuits and flexible electronic packaging. [ABSTRACT FROM AUTHOR]

Effects of a small amount addition of Cr on glass-forming ability (GFA) and mechanical properties of Cu-Zr-Al bulk metallic glass were investigated. The GFA of (CuZrAl)Cr ( x = 0, 0.25, 0.5, 0.75, and 1 at%) alloys tends to decrease with the increasing Cr content. A good correlation between the GFA and the temperature interval of supercooled liquid region Δ T or parameter γ exists in these alloys. Addition of an appropriate amount of Cr can significantly improve the plasticity of the alloys. The bulk metallic glass with x = 0.5 exhibits promising mechanical properties with high fracture strength of 1870 MPa and obvious plastic strain of 2.23%. [ABSTRACT FROM AUTHOR]

The as-cast and the pre-annealed ZrAlNiCuAg bulk metallic glasses were rolled at room temperature to different deformation degrees, and the microstructure and microhardness were examined. It is revealed that no phase transformation occurs in the as-cast/rolled specimen except for localized shear bands, indicating that the material has a good structural stability against plastic deformation. When the glass is pre-annealed in the supercooled liquid region for a short time, however, the stability deteriorates significantly. In this case, rolling deformation results in nanocrystallization in the specimen. The pre-annealed glass has less free volume than the as-cast glass, but it does not exhibit a quicker increase in free volume content during the rolling, suggesting that free volume is prone to annihilate at the crystal/glass interfaces. With nanocrystallization occurred, the microhardness of the pre-annealed specimen decreases at a slower rate than that of the as-cast one during rolling deformation. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) were deposited on bare glass, Au (10 nm)/glass, and Au (50 nm)/glass substrates, and observed using a scanning electron microscope (SEM) operating at different accelerating voltages. Depending on the substrate and accelerating voltage, the CNTs exhibit different levels of contrast. On the poorly conductive glass and Au (10 nm)/glass substrates, electrons are supplied or dissipated through the networked CNTs. This generates a potential difference between the CNTs and the (insulating or poorly conductive) substrates. CNTs are visualized as a result of potential contrast. At a low accelerating voltage (1 kV), the substrate is of higher potential than that of the networked CNTs (the ground potential), and the CNTs exhibit bright contrast. At a high-accelerating voltage (5-10 kV), the potential of the substrate is lower than the networked CNTs, and the CNTs exhibit dark contrast. On the Au (50 nm)/glass conductive substrates, the electrons are supplied through both the Au film and the CNTs, and topographic morphology of CNTs is observed. [ABSTRACT FROM AUTHOR]

The influence of gradient magnetic field on the undercooling behavior of glass-fluxed pure Sb melts was investigated using a superconducting magnet. It was found that under a positive gradient magnetic field, the mean undercooling of pure Sb melts increased with increasing magnetic field intensity. However, under a negative gradient magnetic field, the mean undercooling showed a decreasing tendency following an initial increase with increasing magnetic field intensity. The results were discussed by considering the Lorentz force and the magnetization force imposed by the gradient magnetic field. [ABSTRACT FROM AUTHOR]

The effect of Nb content on the microstructure and mechanical properties of Zr-based bulk metallic glass (BMG) were investigated. The addition of Nb led to the formation of the Zr-based metallic glass composites with a ductile dentritic phase by in situ precipitation. The presence of the in situ precipitated phase enhanced significantly the plasticity of the composite under uniaxial compressive test. The interactions between the precipitated phase and the shear band affect the deformation mechanism and fracture mode of the BMG by enhancing the affecting level of the normal stress on the shear surface, and the constant α in the Mohr–Coulomb criterion can reflect the extent of the interactions among particles and the amorphous matrix. [ABSTRACT FROM AUTHOR]

Bulk Zr60Cu20Pd10Al10 amorphous alloy was rolled at room temperature up to 96% reduction in thickness without fracture. The changes of microstructure and hardness during rolling deformation were investigated by X-ray diffraction, differential scanning calorimetry, high-resolution transmission electron microscopy, and microhardness measurement. It is revealed that the rolling deformation causes the quenched-in nuclei in the glass to grow slowly before a deformation degree of 90%. Substantial nanocrystallization occurs at higher deformation degree, where the softening induced by shear bands can even be compensated by the nanocrystallization. [ABSTRACT FROM AUTHOR]

Based on the structure characteristic of Ti3AlC2 and the easy formation of Ti3Al1 − x Si x C2 solid solution, a Si interlayer was selected to join Ti3AlC2 layered ceramic by diffusion bonding method. Joining was performed at 1,300–1,400 °C for 120 min under 5 MPa load in an Ar atmosphere. The phase composition and interface microstructure of the joints were investigated by XRD, SEM and EPMA. The results revealed that Ti3Al(Si)C2 solid solution formed at the interface. The mechanism of bonding is attributed to silicon diffusing inward the Ti3AlC2. The strength of joints was evaluated by a 3-point bending test. The jointed specimens exhibit a high flexural strength of 285 ± 11 MPa, which is about 80% of that of the Ti3AlC2; and retain this strength up to 1,000 °C. The high mechanical performance of the joints indicates that diffusion bonding via a Si interlayer is effective to bond Ti3AlC2 ceramic. [ABSTRACT FROM AUTHOR]

Weibull modulus of bending strength of nanolayer-grained ceramic Ti3SiC2 was estimated with over 50 specimens, using the least square method, the moment method and the maximum likelihood technique, respectively. The result demonstrated that the m-value of this layered ceramic ranged from 25 to 29, which is much higher than that of traditional brittle ceramics. The reason of high Weibull modulus was due to high damage tolerance of this material. Under stress, delamination and kinking of grains and shear slipping at interfaces give this material high capacity of local energy dissipation and easy local stress relaxation, leading to the excellent damage tolerance of Ti3SiC2. The effect of amounts of specimens on the reliability of the estimated m-values was also investigated. It was confirmed that the stability of the estimated m-value increased with increasing numbers of specimens. The parameter obtained using the maximum likelihood technique showed the highest reliability than other methods. The ranges of failure probability were determined using the Weibull estimates calculated from the maximum likelihood technique. [ABSTRACT FROM AUTHOR]

By heating the admixture of a commercial liquid electrolyte (LB302, 1 M solution of LiPF6 in 1:1 EC/DEC), methyl methacrylate (MMA) and benzoyl peroxide (BPO, initiator), a poly(methyl methacrylate) (PMMA) based gel-polymer electrolyte (GPE) was obtained. AC impedance spectroscopy and cyclic voltammetry were used to evaluate its ionic conductivity and electrochemical stability window. Rechargeable cells LiNi0.8Co0.2O2/Li and LiNi0.8Co0.2O2/graphite with this MMA based GPE were also fabricated via the in-situ thermal polymerization process. This GPE exhibits a high ionic conductivity (over 10−3S cm−1) at room temperature. It is stable in the voltage range between 0 and 4.2 V (vs. Li+/Li). A phenomenon of large initial cell impedance (LICI) was observed for the LiNi0.8Co0.2O2/Li cells but not in LiNi0.8Co0.2O2/graphite cells. After the first several cycles, the cell impedance decreases substantially and reversible charge–discharge capacity can be obtained. This in-situ polymerization method provides a way to produce GPE cells. [ABSTRACT FROM AUTHOR]

This work studied the effects of oxygen contamination in the argon shielding gases on weld microstructures and properties during laser welding of commercially pure titanium thin sheets. The experimental results, mainly analyzed by optical and scanning electron microscopy and mechanical testing, have indicated correlations between weld surface colour, weld microstructure and mechanical properties (strength, ductility, hardness). As the oxygen content increased, the weld surface colour changed from silver, straw to blue while the surface hardness continued to increase. On the other hand, with the increasing of oxygen content, the weld strength increased first and then decreased because the microstructure changed from mainly serrated alpha in welds made with pure argon shielding gas to mainly acicular and platelet alpha. Practical guidelines are also discussed, based on the study, to deal with shielding deficiencies in laser welding of titanium. [ABSTRACT FROM AUTHOR]

The crystallization kinetics of Zr60Al15Ni25 bulk glassy alloy under isochronal and isothermal conditions has been investigated by differential scanning calorimetry (DSC). The microstructure of as-cast Zr60Al15Ni25 bulk glassy alloy is observed by high-resolution electron microscopy (HREM). It is found that there exist nanocrystals with a size of about 7 nm in the glassy matrix, which are not observed in the XRD image. The results of Kissinger analysis show that the effective activation energies for glass transition (457 kJ/mol) and crystallization (345 kJ/mol) are high, indicating that it has large thermal stability against crystallization. The crystallization of Zr60Al15Ni25 bulk glassy alloy under isothermal annealing can be modeled by the Johnson-Mehl-Avami equation. The crystallization kinetics parameters show that the isothermal crystallization starts from the growth of the pre-existing nanocrystals and the crystallization process is diffusion-controlled. [ABSTRACT FROM AUTHOR]

A new tungsten matrix composite containing 30 vol% titanium carbide particles (W-TiC) produced by sintering under 20 MPa pressure at 2000°C in a vacuum has been developed in order to improve the elevated temperature strength of tungsten. Flexural strength tests of the W-TiC composite in the temperature range 20–1200°C showed that the strength was significantly increased by the presence of TiC particles. The flexural strength at 1000°C was 1155 MPa, which was much higher than that at 20°C (770 MPa). Microstructural observations showed that a interdiffusion zone was produced at the W matrix-TiC particle interface, and a strong bond was formed between TiC and W, which was very beneficial to the elevated temperature mechanical properties. The mechanisms of fracture at 20°C and 1000°C were investigated. The fracture at 20°C was brittle. There was a growth-coalescence process for the initial cracks during the fracture process of the W-TiC composite at 1000°C, and the W matrix exhibited ductile tearing. The excellent elevated temperature strength of W-TiC composite was attributed to the brittle-ductile transition in the W matrix, which allows more effective strengthening from TiC particles. [ABSTRACT FROM AUTHOR]

The sintering behavior of three fine industrial SiC powders (two 6H(α)-type and one 3C(β)-type) has been comparatively investigated. The powders were pressureless sintered with B4C and C additives between 1950°C and 2250°C in a high temperature dilatometer with flowing Ar atmosphere. The densification and shrinkage rate curves, polytype content, and grain growth were correlated with physical and chemical characteristics of starting powders. One of 6H(α)-type powders presented good sinterability only after extensive milling, even though it presented small average particle size, narrow particle size distribution and high specific surface area. The main difference in densification behavior among powders was the narrower shrinkage rate curve of β-SiC powder, with its maximum shifted to higher temperature. Grain growth and phase transformation simultaneously occurred. In α-SiC, 6H polytype partially transformed to 4H. This transformation was favored by aluminum impurity and resulted in a microstructure with more elongated grains. In β-SiC, 3C transformed mainly to 6H, 15R and 4H, introducing many stacking faults which resulted in elongated SiC grains. [ABSTRACT FROM AUTHOR]

In order to improve the elevated temperature ablation resistance of the copper infiltrated tungsten materials (Cu/W) which are used as the rudders of the rocket motors at present, a new kind of tungsten matrix composites reinforced by 30 vol% zirconium carbide particles (ZrCp/W) was developed, and the elevated temperature ablation resistance and thermophysical properties of the new materials were investigated. The values of the mass ablation rate and linear ablation rate of ZrCp/W were much lower than that of Cu/W, which indicated that the addition of ZrC particles in tungsten matrix remarkably increased the ablation resistance. Thermal thermochemical oxidation of tungsten and ZrC particles was the main ablation mechanism of ZrCp/W. A self-made dynamic responding multi-wavelength pyrometer was employed to measure the ablated surface temperatures and a thermal couple was employed to measure the back surface temperatures. The important temperature curves of the ablated surface and back surface of the specimens were successfully detected online, which indicated that ZrCp/W has good thermal shock resistance. The present of ZrC particles in tungsten matrix remarkably decreased the thermal conductivity and thermal diffusivity of the ZrCp/W composites, which is very useful for increasing the elevated temperature ablation resistance of the composites. The excellent elevated temperature ablation resistance of ZrCp/W is attributed to the lower thermal conductivity, lower thermal diffusivity, oxidation resistance and high melting points. The good properties of ZrCp/W makes it be suitable for the rudders for rocket motors instead of Cu/W. [ABSTRACT FROM AUTHOR]

BAS glass-ceramic composites reinforced with different volume fractions (0, 10, 20, 30, 40 vol%) of SiC whiskers were successfully fabricated by a hot-pressing method. The microstructure, whisker/matrix interface structure, phase constitution and mechanical properties of the composites have been systematically studied by means of SEM, TEM, XRD techniques as well as three-point bending tests. It was demonstrated that the incorporation of SiC whiskers could significantly increase the flexural strength and fracture toughness of BAS glass-ceramic matrixes. The celsian seeds can effectively promote the hexacelsian-to-celsian transformation in BaAl2Si2O8. The active Al2O3 added to the BAS matrix obviously reduced the amount of SiO2 in the matrix and formed needle-like mullite. The high temperature strengths of the composites were also investigated. [ABSTRACT FROM AUTHOR]

20vol%SiCw/BAS (barium aluminosilicate) composites with as-received, acid-leached and heat-treated whiskers were fabricated by a hot-pressing technique and their mechanical properties were evaluated. The whiskers used in these composites were characterized using Auger electron spectrometry (AES) and scanning electron microscopy (SEM), and the observations were correlated with the mechanical properties. The results show that the oxygen content of the whisker surfaces was reduced by the hydrogen fluoride (HF) acid-leaching treatment and the surface geometry of whiskers was smoothed by the heat-treatment in an inert gas atmosphere. The corresponding composites show an obvious increase (18% and 31%, respectively) in toughness compared with the composites reinforced with as-received whiskers. Fracture surfaces revealed evidence of toughening by the mechanisms of crack deflection, crack bridging and whisker pullout for the composites with surface treated whiskers. [ABSTRACT FROM AUTHOR]

The effect of solidification history on the resultant microstructures in atomized Al–3Fe and Al–7Fe powders is studied, with particular emphasis on the relationships between droplet size, undercooling and phase stability. The atomized Al–Fe powders exhibit four microstructural features, i.e. Al3Fe phase, Al + Al6Fe eutectic, α-Al dendrite and a predendritic structure. The presence of these is noted to depend on a kinetic phase competitive growth mechanism, which was determined by the initial undercooling experienced by the powders. The results of scanning electron microscope analysis demonstrate that the content of Fe in the α-Al phase increases with decreasing powder particle size, i.e. for Al–3 wt % Fe powders, the content of Fe in the α-Al phase is 2.21 and 2.56 wt % corresponding to powder particle sizes of 90 and 33 μm, respectively; for Al–7 wt % Fe powders, the content of Fe in the α-Al phase is 5.51 and 5.98 wt % corresponding to powder sizes of 90 and 33 μm, respectively. In the present study, homogeneous nucleation undercooling, corresponding to the α-Al phases, is also estimated using an existing correlation. [ABSTRACT FROM AUTHOR]

Room temperature tensile properties of polycrystal Ti–47Al–2Mn–2Nb alloy with near lamellar (NL) microstructures were investigated at the strain rates between 10−5 and 1000 s−1 using a self-designed Split-Hopkinson tensile bar setup with a rotating disk and conventional testing machine. It was found that tensile ductility varies within a narrow range with the strain rate, while dynamic strengths (σd) of the alloy are obviously higher than static strengths (σs). There exists linear relationship between σs and the logarithm of the strain rate (ln έ), and between σd and the strain rate itself (έ). Fractography analysis indicates that the alloy fractures in a mixed mode of predominant transgranular cleavage and minor intergranular cracking under static and dynamic strain rates. Environmental effect is excluded from the main cause for the room temperature brittleness of the investigated alloy. [ABSTRACT FROM AUTHOR]

Describes the storage characteristics of LiNi0.85Co0.15O2 in air as cathode material for lithium-ion batteries. Factor influencing the performance of lithium-ion batteries; Identification of a powder sample; Performance of morphological observations; Analysis of the phases occurring in the sample powder during storage.

Discusses the process of brazing silicon nitride ceramic using a copper palladium titanium filler alloy for high-temperature applications. Improving the thermal and oxidation resistance of ceramic joint; Pressure sintering process; Attractive material for engineering applications; Joining techniques; Morphology and elemental analysis results.

A correction to the article "Joint formation mechanism and strength in resistance microwelding of 316L stainless steel to Pt wire" that was published in the previous issue is presented.