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Al doped nanocrystalline ZnO (∼30 nm) with composition Zn 1−x Al x O (0.005 < x < 0. 03) were synthesised by pyrophoric technique and sintered at 650 °C. We performed detailed electron spin resonance (ESR) studies on this system to understand the spin ordering and magnetism. The spin canting order and magneto-crystalline anisotropy obtained through ESR measurements follow each other and have a broad peak for Al doping concentration of 0.02, which also matches with the saturation magnetisation ‘M s ’ maximum, that is obtained by direct magnetisation measurement using VSM. However, it is intriguing that the spin susceptibility has a broad minimum around the same doping level (0.02). Through the ESR measurement this observed weak ferromagnetism is attributed to the spin canted magnetism in the system. Other supportive experimental data from UV–Vis, PL and Raman analysis give a clear picture of defect structures in the form of oxygen vacancies that faciliates the occurrence of room temperature ferromagnetism which of course is through spin canting mechanism. [ABSTRACT FROM AUTHOR]

Highlights: [•] Effect of Sn on the indentation size effect in Ti–Fe–(Sn) has been explored. [•] Fitting through ISE models point the existence of strain gradient beneath indenter. [•] Correlation has been established between dislocation density, grain size and ISE. [•] ISE in Ti–Fe–Sn ultrafine composites requires a dislocation density of ∼1014–1016/m2. [Copyright &y& Elsevier]

Abstract: The effect of superficial CeO2 coating on the oxidation behavior of Ti–6Al–4V has been studied under isothermal and cyclic heating conditions in the temperature range of 923–1223K in dry air. During the early periods of exposure, the oxide scale grows obeying near linear followed by near parabolic kinetics and consists of alternate layers of α-Al2O3 and TiO2. The mass gain of the uncoated alloys is found to be two times higher than that of the coated one in the temperature range of 923–1123K up to 36h of exposure. The scale composition on the bare or coated alloy is found to depend both on the temperature and on the time of exposure. During cyclic exposure, the scale suffers spallation for both the bare and the coated alloy, which has been attributed to insufficient plasticity of the scale. [Copyright &y& Elsevier]

Abstract: A clean signature of room temperature multiferroicity in Bi1.2Gd0.1Fe0.8O3 ceramics is observed. Samples were prepared by slow step sintering technique at 850°C. Impurity peaks normally present in original BiFeO3 are completely suppressed with the increase of Bi concentration. Apart from this, structural transformation took place from R3 C to Pn21 a space group and a clear orthorhombic grain growth habit is seen by SEM microstructure. Suppression of impurity phases favors the reduction of mobile oxygen vacancies and hence reduces leakage current for which ferroelectric properties of Bi1.2Gd0.1Fe0.8O3 are enhanced. We argue that the addition of Gd is likely to suppress the spiral spin modulation and at the same time increase the canting angle which favors the enhanced ferromagnetism. Excess Bi is expected to act as point defects and occupy interstitial positions which in turn surrounded by oxygen vacancies and is likely to promote defect driven ferromagnetism with enhanced spin and electric polarization. This finding encourages further revaluation of long-discounted BiFeO3 for multiferroics research. [ABSTRACT FROM AUTHOR]

Abstract: Ultrafine structured Ti70.5Fe29.5 and Ti67.79Fe28.36Sn3.85 eutectic rods comprising of β-Ti and TiFe phases were prepared by copper mould casting. The corrosion and passivation behaviour were investigated in halide free aqueous media (pH 1–13) by means of potentiodynamic polarisation and potentiostatic current transient measurements. Both eutectic alloys exhibit excellent corrosion resistance due to spontaneous passivation. The passive film compositions grown several nanometres on single phase polycrystalline specimens were analyzed with Auger electron spectroscopy. They consist of oxidized Ti and Fe species. Layers grown in strongly acidic environment are depleted in Fe. Sn was detected only on layers grown on the constituent β-Ti phase and only in the metallic state. The pitting susceptibility was investigated in strongly acidic media (pH≤1) containing 0.1–3M of chloride ions. The Sn-containing eutectic alloy was found to be more susceptible to pitting corrosion. [Copyright &y& Elsevier]

Abstract: The effect of Al content on the glass formation and mechanical properties was studied for (Cu50Zr50)100−x Al x (x =0, 4, 5, 7) bulk metallic glasses. The crystallization temperatures of fully amorphous Cu50Zr50, Cu48Zr48Al4, Cu47.5Zr47.5Al5 and Cu46.5Zr46.5Al7 as-cast rods are 724K, 753K, 758K and 782K, respectively. The mechanical properties were investigated under compression at room temperature. As-cast Cu46.5Zr46.5Al7 shows the highest yield strength (1867MPa), whereas Cu47.5Zr47.5Al5 shows the largest fracture strain of 11.2%. The fracture surfaces of the compressed samples were investigated by scanning electron microscopy and their morphology has been correlated with the compressive plasticity. [Copyright &y& Elsevier]

Abstract: To circumvent the limited plasticity of bulk metallic glasses (BMGs), heterogeneous materials with glassy matrix and different type and length-scale of heterogeneities (micrometer-sized second phase particles or fibers, nanocrystals in a glassy matrix, phase separated regions, variations in short-range order by clustering) have been reported. We developed bulk metallic glasses and glass matrix composites in martensitic Zr–Cu-base alloys. Large plasticity can be obtained from microstructure consisting of either a glassy structure, or for alloys with martensitic second phase embedded in a glassy matrix. This type of glasses and glass–matrix composites are able to achieve high strength together with pronounced work-hardening. We explore the possibilities to synthesize such in situ composite microstructures based on shape memory alloys (“M-Glasses”) through metal mold casting. [Copyright &y& Elsevier]

Abstract: Investigation of the microstructure of a compressed Ti66.1Cu8Ni4.8Sn7.2Nb13.9 nanostructure–dendrite composite reveals that the deformed bcc β-Ti dendrites form a stepped morphology at the interfaces between the individual dendrites and the nanostructured matrix of hcp α-Ti and bct Ti2Cu phases. Furthermore, there is a unique stained contrast during the propagation and the interaction of the shear bands in the dendrites indicating a local structural change near to the apex of the shear bands in the dendrite. In contrast, the shear bands pass through coherent grain boundaries between the hcp α-Ti and the bct Ti2Cu phases of the nanostructured matrix. [Copyright &y& Elsevier]

Abstract: An ultra-fine eutectic structure has been obtained in the Ti70.5Fe29.5 binary alloy by slow cooling from the melt through arc melting and cold crucible rod casting. The addition of 3.85 at.% Sn to the binary Ti–Fe alloy induces a change of the morphology of the eutectic and increases the volume fraction of the FeTi (Pm3m) phase. A significant improvement of the plastic deformability of the ternary alloy has been observed under uniaxial compressive loading resulting in 16% strain to failure compared to 3.4% for binary Ti70.5Fe29.5. The morphology of the eutectic colonies, their refinement and supersaturation of the β-Ti phase are crucial factors for improving the ductility of the ultra-fine eutectic alloys. [Copyright &y& Elsevier]

Abstract: The deformation behavior of multicomponent Ti66Cu8Ni4.8Sn7.2Nb14 composite containing primary dendrites embedded in a nanoeutectic matrix was studied under uniaxial compression. The evolution of slip and shear bands has been investigated at various stages of deformation. This type of advanced composite not only displays a high compressive plasticity of 31.8%, but also exhibits high fracture strength of ≈2.02GPa (true fracture strength 1.38GPa). Pronounced work hardening was observed after yielding. The surface deformation morphology reveals that the work hardening behavior of the composite is related to the plastic deformation of the dendritic phase through slip bands and the interaction of shear bands in the nanostructured matrix with the hardened dendrites. The nucleation of shear band occurs at a certain amount (8%) of plastic deformation at the dendrite–nanoeutectic matrix interface. The final stage of compression proceeds through passing of the shear bands through the work-hardened dendrites into the nanoeutectic matrix, whereby the propagation of the shear bands in the matrix is retarded by the nanoscale phases. [Copyright &y& Elsevier]

Nanotwinned α-brass (Cu–30 wt.% Zn) with varying lamellae thickness in the range of 28–170 nm, has been produced by cryorolling (CR). The effect of CR strain ( ɛ CR = 0.2–0.95) on the evolution of homogeneity and refinement in terms of twin lamellae thickness, twin spacing, and their distribution, have been studied using high-resolution transmission electron microscopy (HRTEM) and microhardness measurements. Analysis of X-ray peak broadening has shown that the crystallite size reduces down to 20 nm at ɛ CR = 0.95, which scales with the subgrain size in preexisting twin lamellae, as revealed under HRTEM. The effect of dislocation density and crystallite size on the strength of nanotwinned brass has been correlated using an analytical model. [ABSTRACT FROM AUTHOR]

Abstract: Yielding in metallic glasses is often described in terms of the Mohr–Coulomb criterion, τ + μσ ≥ τ 0. It suggests that a material yields when a combination of shear (τ) and normal stresses (σ), linked through the friction coefficient (μ), reaches the critical shear stress (τ 0). In this paper, an increase of the friction coefficient for increasing Poisson ratio is foreseen, if the elastic limit observed under uniaxial (tensile or compressive) and shear stresses remain constant. Experimental values of Young and shear moduli and Poisson ratio of metallic glasses have been collected from the literature. Compressive and tensile yield stresses have been also collected and elastic limits have been calculated. The elastic limit observed under compressive stress decreases with increasing Poisson ratio and it appears similar for metallic glasses based on the same metals. The values of the friction coefficient for metallic glasses have been obtained from the fracture angle observed under uniaxial stress (compressive or tensile) and from the ratio between compressive and tensile strength. Experimental data of the friction coefficient appear rather scattered and a clear trend as a function of Poisson ratio cannot be outlined. The increase of toughness of metallic glasses with increasing Poisson ratio has been ascribed to the corresponding reduction of the compressive elastic limit. [Copyright &y& Elsevier]

Abstract: In situ optimized heat treatment in high-energy monochromatic beam of synchrotron light was conduced to generate fine nanoparticle dispersions in Zr-based alloys. Effect of embedded nanocrystals on the mechanical properties of our BMG-composites was investigated by compressive testing at room temperature. We found that the newly created nanostructured composites show good strength at high ductility with no work hardening. Based on TEM observations, a new mechanism was proposed which compensates for shear softening. The nanocrystals initially smaller than the elementary shear band were expected to growth in active shear band during deformation. [Copyright &y& Elsevier]

Abstract We report the evolution of nanocrystalline γ-Ni of 3–7 nm size along with amorphous phase in (Ni 0.50 Fe 0.50) 70.5 B 17.7 Si 7.8 Ti 4 (at.%) upon mechanical alloying of the elemental powder mixture up to 36 h. The effect of milling time on the nanostructure, thermal stability and magnetic properties, have been investigated using x-ray diffraction, differential scanning calorimeter, transmission electron microscope, and vibrating sample magnetometer. The lattice parameter of the γ-Ni phase gradually decreases from 0.3607 nm for 9 h milling down to 0.3554 nm upon 36 h of milling. A first-order magnetic transition has been identified using Arrott plot analysis at Curie temperature (T C) of 608 K along with a large magnetic entropy change (Δ S M) of 0.45 J/kg.K at an applied field of 13800 Oe, and relative cooling power (RCP) of 10.15 J/kg. The effects of nanostructure and phase constituents on the thermal stability, T C , magnetization and coercivity, have been correlated. Highlights • (Ni 0.50 Fe 0.50) 70.5 B 17.7 Si 7.8 Ti 4 (at.%) has been prepared by mechanical alloying. • Heat-treated powder contain nanocrystalline γ -Ni phase with 13–22 nm size. • A first order transition has been identified. • The transition involves a large entropy change of |- ΔS M | = 0.45 J/kg.K at 13800 Oe. [ABSTRACT FROM AUTHOR]

Abstract: Bulk Zr50Cu50 partially crystallized glassy specimens have been produced by powder metallurgy methods. Zr50Cu50 powder has been prepared by controlled milling of melt spun glassy ribbons and subsequently consolidated by hot pressing into bulk cylindrical samples of 10mm diameter and 10mm length. The consolidated material exhibits interesting mechanical properties, namely, a perfect elastic regime of 1.5%, high strength of about 1350MPa and hardness of 4.80GPa. However, no macroscopic ductility is visible, most likely due to the residual porosity of the consolidated specimens. These results indicate that powder metallurgy methods may become a valid alternative to casting techniques for the production of glassy and partially crystallized Zr-based alloys. [Copyright &y& Elsevier]

Abstract: The mechanical behaviour upon compression of (Cu0.50Zr0.50)100−x Al x (x =4, 5, 7) rods with 2 and 3mm diameter was systematically studied and compared with the literature data. Fully amorphous bulk metallic glasses (x =5, 7) show little permanent deformation and reproducible yield stress values. The remarkable fracture strain, observed for some apparently X-ray diffraction amorphous samples (x =4), was found to be due to significant amounts (at least 20%) of the B2-CuZr crystalline phase. The effect of possible flaws on the external surface of the rods was evaluated by mechanical testing of either as cast and machined samples. [Copyright &y& Elsevier]