The effects of an axial high magnetic field on the growth of the α-Al dendrites and the alignment of the iron-intermetallics (β-AlSiFe phases) in directionally solidified Al–7 wt% Si and Al–7 wt% Si–1 wt% Fe alloys were investigated experimentally. The results showed that the application of a high magnetic field changed the α-Al dendrite morphology significantly. Indeed, a high magnetic field caused the deformation of the α-Al dendrites and induced the occurrence of the columnar-to-equiaxed transition (CET). It was also found that a high magnetic field was capable of aligning the β-AlSiFe phases with the <001>-crystal direction along the solidification direction. Further, the Seebeck thermoelectric signal at the liquid/solid interface in the Al–7 wt% Si alloys was measured in situ and the results indicated that the value of the Seebeck signal was of the order of 10 µV. The modification of the α-Al dendrite morphology under the magnetic field should be attributed to the thermoelectric magnetic force acting on the α-Al dendrites. The magnetization force may be responsible for the alignment of the β-AlSiFe phases under the magnetic field.

The flow behavior of forged commercial purity (CP) titanium powder compact was studied by developing a processing map. CP titanium powder was sintered to 94% relative density, then hot compressed in a Gleeble thermal–mechanical simulator at strain rates ranging from 0.001 to 10 s−1 and deformation temperatures ranging from 600 to 800 °C. The hot forging process improved the densification to 98–99.9% and reduced the grain size from 93 to 10 µm by the occurrence of dynamic recrystallization. The fully dynamic recrystallization region is in the range of deformation temperature of 750–800 °C and strain rate of 0.001–0.01 s−1, with a power dissipation efficiency higher than 40%, determined by constructing a processing map and analyzing the volume fraction of dynamic recrystallization. This research provides a guide for powder compact forging of power metallurgy titanium by providing the hot compression parameters, which can lead to an improved microstructure and densification.

Sn–Ag–Cu solder interconnects were made by solidifying the solder balls in a magnetic field and subsequently tested for their electromigration behavior. The orientation of the tin grains was analyzed by electron backscattered diffraction. It was found that the c-axis of Sn grain tended to rotate away from the direction of the magnetic field during solidification, resulting in an enhanced electromigration resistance for the solder joint when the current was applied along the direction of the magnetic field, as evidenced by a smaller electromigration-induced polarity effect in the growth of the interfacial intermetallic compound. Such a reduced polarity-effect of electromigration is shown to agree well with the anisotropy in the diffusivity of the active diffusion species, Cu, in the tetragonal Sn. The difference of free energy change caused by the anisotropy in the magnetic susceptibility of the tetragonal Sn during solidification is suggested to be the main factor for this phenomenon.

Amorphous and nanocrystalline soft magnets have been investigated extensively in the past two decades. Many materials with attractive soft magnetic properties contain boron, which improves the glass formability, thermal stability and prevents undesirable grain growth. The high price of boron, however, makes the development of new soft magnetic materials and alternative synthesis routes important. We report here a synthesis of cobalt-rich alloys by substituting boron carbide for elemental boron to achieve significantly lower cost. Ribbons produced with and without boron carbide substitution were observed to exhibit comparable soft magnetic properties while the former results in 31–48% cost reduction. Extrapolating this idea to commercial VITROVAC 6025 and 6150, the cost reductions were calculated to be 56 and 50%, respectively, while both synthesis routes produced ribbons of similar soft magnetic properties. Our work here provides an attractive route to reduce the cost and increase the market competitiveness of soft magnets.

In this paper, a novel method is proposed to determine surface residual stress components and their directions based on the spherical indentation. To obtain the direction and the components of a uniaxial or biaxial residual stress, the relationship between the pile-up deformation around an indentation after unloading and the residual stress was firstly systematically studied and established by using numerical simulation. Through theoretical analysis and numerical simulation, we found that the position of the maximum residual stress is dependent on the maximum pile-up around an indentation after unloading. The direction and components of residual stress can be correctly determined by the unique relationship between pile-up after unloading and biaxial residual stress. This conclusion has been verified by the experiment results in the residual stress measurements of a welded specimen with spherical indentation and x-ray diffraction methods. Meanwhile, the influences of friction between the object surface and the indenter, the material hardening exponent of the specimen, and the elastic deformation upon the residual stress are discussed.

In this study, the interfacial adhesion of Cu and TiN on an annealed borophosphosilicate glass (BPSG) in a multilayer material stack was investigated. The two material systems, Cu/BPSG and TiN/BPSG, are representatives for weak and strong interfaces, respectively. A weak and a strong interface was chosen to identify possible differences in the fracture path selection for the multilayer material systems. To investigate this, in situ 4-point-bending experiments were performed under an optical microscope and in a scanning electron microscope. Complementary ex situ 4-point-bending experiments were carried out on the identical material systems. These tests revealed that for the two analyzed systems there is a large discrepancy in the success rate of failure along the interface of interest, which is a prerequisite for determining the corresponding interface energy release rate. This phenomenon can be understood by using theoretical findings of earlier studies reported in the literature, which are in agreement with the experimental outcome of the in situ 4-point-bending measurements presented here.

In this study, a method using dual triangular pyramidal indenters is suggested for material property evaluation. First, we demonstrate that the load–depth curves and the projected contact areas from conical and triangular pyramidal indentations are generally different. Nonequal projected contact areas of two indenters and nonplanar contact line of Berkovich indenter are the main sources of different indentation characteristics of two indenters. For this reason, an independent approach to the triangular pyramidal indentation is needed. With finite element (FE) indentation analyses for various materials, we investigate the relationships between material properties, indentation parameters, and load–depth curves. Based on the FE solutions, we suggest mapping functions for evaluating material properties from indentations by two triangular pyramidal WC indenters, which differ in their centerline-to-face angles. Elastic modulus, yield strength, and strain hardening exponent are obtained with an average error of <3%.

This investigation reports mechanical properties of the exoskeleton of deep sea shrimp, Rimicaris exoculata, at temperatures ranging from 25 to 80 °C measured using nanoindentation experiments. The measured properties are compared with the corresponding shallow water shrimp (Pandalus platyceros) exoskeleton properties. Scanning electron microscopy suggests that both types of shrimp exoskeletons have the twisted plywood, Bouligand structure. However, they differ in the volume fraction and distribution of mineral content. The variations in the nanoindentation measured hardness values of the examined shrimp exoskeletons are found to be strongly correlated with the corresponding compositional difference between the two exoskeleton types. Nanoindentation creep strain rate measurements are performed to provide an assessment of the two types of exoskeleton for the role of proteins and minerals to cause difference in behavior and properties between the two shrimp species. The measured creep load–depth data are fitted with a viscoelastic creep function to find the creep compliance as a function of experimentally varying temperature and in the context of natural variations in mineral content.

We report on the high catalytic activity of iron based metallic glass (MG) particles in dissociating direct blue dye (C32H20N6Na4O14S4) (DBD), a toxic water pollutant. We adopted high speed mechanical milling to activate the FeMG particles (of nominal composition Fe48Cr15Mo14Y2C15B6) and optimized the morphology and the particle size to achieve complete degradation of DBD in less than 20 min. The surface morphology and the particle size of the activated particles were characterized using scanning electron microscopy and transmission electron microscopy. They were found to have corrugated edge like catalytically active surfaces after mechanical activation. The dye degradation rate of the activated MG powder was characterized via UV–visible absorption spectroscopy. The rate of dye degradation was significantly faster for the activated particles (within 20 min), compared to both pristine FeMG particles as well as elemental iron particles. In addition, the dye degradation mechanism was studied using Raman and infrared spectroscopy. The catalytically activated surfaces are believed to break the –C–H–, –C–N–, and –N=N– bonds, resulting in complete degradation of DBD.

The Ag3PO4/C3N4 composites with improved photocatalytic activity were prepared by a facile in situ deposition of Ag3PO4 particles on the surface of C3N4 sheets and characterized by x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, UV–vis diffuse reflectance absorption spectra, Fourier transform infrared spectra, and photoluminescence spectra. The photocatalytic degradation of Rhodamine B (RhB) over the Ag3PO4/C3N4 composites was investigated and optimized, indicating that the optimal amount of Ag3PO4 in the composites was 90 wt%. The remarkably improved photocatalytic activity of Ag3PO4/C3N4 composites could be attributed to the effective separation of photogenerated charge carriers. The photoelectrochemical measurements confirmed that the charge separation efficiency was improved for the formation of composites. Moreover, the tests of radical scavengers demonstrated that h+ and ·O2− were the main active species for the degradation of RhB.

The onset of a diffusive phase transformation in thin film Zn0.70Mg0.29Ga0.01O deposited on c-oriented sapphire (α-Al2O3) was explored using dynamic heating experiments in a laser pulsed atom probe tomography (APT) instrument and correlated with transmission electron microscopy (TEM). Specimens were laser irradiated using 100–1000 pJ pulse energies with initial temperatures between 50 and 300 K for up to 8.64 × 1010 pulses. Using a finite element model, it was possible to estimate the temperatures reached by the specimen during laser pulsing, which were calculated to be 300 K to above 1000 K. Due to the small sample volume, quench rates were estimated to be 1013 K/s, allowing for nanosecond temporal resolution during the in situ heating experiments. The formation of Mg-spinel (MgAl2O4) at the transparent conductive oxide/α-Al2O3 substrate interface was observed using electron diffraction and confirmed by atom probe analysis. Subnanometer spatial resolution in the atom probe data reconstructions allowed for near atomic level diffusion to be observed. This work demonstrates the feasibility of conducting these experiments in situ using a combined TEM and APT instrument.

The mechanisms of densification and creep were examined during spark plasma sintering (SPS) of alumina doped with a low and high level of zirconia or yttria, over a temperature range of 1173–1573 K and stresses between 25 and 100 MPa. Large additions of yttria led clearly to in situ reactions during SPS and the formation of a yttrium-aluminum garnet phase. Dopants generally lead to a reduction in the densification rate, with substantial reductions noted in samples with ∼5.5 vol% second phase. In contrast to a stress exponent of n ∼ 1 for pure alumina, the doped aluminas displayed n ∼ 2 corresponding to an interface-controlled diffusion process. The higher activation energies in the composites are consistent with previous data on creep and changes in the interfacial energies. The results reveal a compensation effect, such that an increase in the activation energy is accompanied by a corresponding increase in the pre-exponential term for diffusion.