Corrosion of nanocrystalline Ni–W alloys in alkaline and acidic 3.5 wt.% NaCl solutions

The corrosion behaviour of reverse-pulse electrodeposited nanocrystalline nickel tungsten alloys (nc Ni–W) in pH 3 and 10 3.5 wt.% NaCl solutions is investigated and analysed as a function of grain size. A potentiodynamic polarisation study reveals that the corrosion rate of nc Ni–W generally increases with the reduction of grain size in alkaline condition, but decreases with the reduction of grain size in acidic environment. Furthermore, for both environments, nc Ni–W alloys exhibit superior localised corrosion resistance than a microcrystalline Ni control specimen. Factors controlling the corrosion behaviour of these materials, including grain size, tungsten content, passivation and crystallographic texture are addressed.     

Strain rate-dependent deformation in bulk metallic glasses

Metallic glasses have metastable structures. As a result, their plastic deformation is dependent upon structural dynamics. In the present paper, we present data obtained from Zr-base and La-base metallic glasses and discuss the kinetic aspects of plastic deformation, including both homogeneous and heterogeneous deformation. In the case of homogeneous deformation (typically occurring in the supercooled liquid region), Newtonian behavior is not universally observed and usually takes place only at low strain rates. At high strain rates, non-Newtonian behavior is usually observed. It is demonstrated that this non-Newtonian behavior is associated with in situ crystallization of the amorphous structure. In the case of heterogeneous deformation (occurring at room temperature), deformation is controlled by localized shear banding. The plastic deformation of a La-base metallic glass is also investigated using instrumented nanoindentation experiments over a broad range of indentation strain rates. At low rates, the load-displacement curves during indentation exhibit numerous serrations or pop-ins, but these serrations become less prominent as the indentation rate is increased. Using the tip velocity during pop-in as a gauge of serration activity, we find that serrated flow is only significant at indentation strain rates below a certain critical value.     

The Effect of Parameter Estimation on Upper‐sided Bernoulli Cumulative Sum Charts

The Bernoulli cumulative sum (CUSUM) chart has been shown to be effective for monitoring the rate of nonconforming items in high‐quality processes where the in‐control proportion of nonconforming items (p₀) is low. The implementation of the Bernoulli CUSUM chart is often based on the assumption that the in‐control value p₀ is known; therefore, when p₀ is unknown, accurate estimation is necessary. We recommend using a Bayes estimator to estimate the value of p₀ to incorporate practitioner knowledge and to avoid estimation issues when no nonconforming items are observed in phase I. We also investigate the effects of parameter estimation in phase I on the upper‐sided Bernoulli CUSUM chart by using the expected value of the average number of observations to signal (ANOS) and the standard deviation of the ANOS. It is found that the effects of parameter estimation on the Bernoulli CUSUM chart are more significant than those on the Shewhart‐type geometric chart. The low p₀ values inherent to high‐quality processes imply that a very large, and often unrealistic, sample size may be needed to accurately estimate p₀. A methodology to identify a continuous variable to monitor is highly recommended when the value of p₀ is low and the required phase I sample size is impractically large. Copyright © 2012 John Wiley & Sons, Ltd.     

Electrodeposited Al–Mn alloys with microcrystalline,nanocrystalline, amorphous and nano-quasicrystalline structures

Al–Mn alloys with Mn content ranging from 0 to 15.8 at.% are prepared by electrodeposition from an ionic liquid at room temperature, and exhibit a remarkably broad range of structures. The alloys are characterized through a combination of techniques, including X-ray diffraction, electron microscopy and calorimetry. For alloys with Mn content up to 7.5 at.%, increasing Mn additions lead to a decrease in grain size of single-phase microcrystalline face-centered cubic (fcc) Al(Mn). Between 8.2 and 12.3 at.% Mn, an amorphous phase appears, accompanied by a dramatic reduction in the size of the coexisting fcc crystallites to the ～2–50 nm level. At higher Mn contents, the structure nominally appears entirely amorphous, but is shown to contain order in the form of pre-existing nuclei of the icosahedral quasicrystalline phase. Additionally, nanoindentation tests reveal that the nanostructured and amorphous specimens have very high hardnesses that exhibit complex trends with Mn content.     

Discovery of the silver isotopes

Thirty-eight silver isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.     

Product variety management

A great challenge facing industry today is managing variety throughout the entire products life cycle. Drivers of products variety, its benefits, pre-requisites and associated complexity and cost are presented. Enhancing consumers’ value through variety and approaches for achieving it efficiently including modularity, commonality and differentiation are discussed. Variant-oriented manufacturing systems paradigms, as enablers of product variety, and the effective co-development of variants and their manufacturing systems to ensure economic sustainability are reviewed. Industrial applications and guidelines to achieve economy of scope with advantages of economy of scale are discussed. Perspectives and insights on future research in this field are offered.     

Microstructure and fracture of anomalous eutectic silicon-disilicide composites

Microstructural and mechanical investigations have been performed on a new class of silicon-disilicide eutectic composites comprising a Si matrix and reinforcing (Cr,V)Si₂ disilicide phase. These composites are cast from the liquid and undergo anomalous eutectic solidification, during which loosely coupled growth of the consitutent phases results in a wide range of eutectic morphologies depending on the volume fraction (V_f) of the minor phase. As the chromium content is varied from 0 to 20 wt. %, the eutectic morphology changes from an irregular fibrous (V_f = 7%) to an irregular plate (V_f = 20%) to an irregular/complex regular plate (V_f = 24%) to a pseudo-colony (V_f = 40%) structure. Chevron-notched beam fracture toughness values for the composites were measured to be around 2–3 MPa m^1/2 – more than twice that of unreinforced Si and comparable to SiC. This toughening is due to crack deflection and bridging mechanisms resulting from the weak interfaces between the Si matrix and (Cr,V)Si₂ reinforcements. The experimental toughness values are reasonably well modeled using a conventional crack bridging model with some discrepancies that highlight the complexities arising from the anomalous eutectic structures.     

Condition based factory planning

Consecutive planning approaches, common in the theory of factory design today, fail to support planning projects in practice. They neglect the interactions and dynamics in the planning task and project as well as the subjectivity introduced by the different stakeholders. Unconsidered interactions, conflicting motives and inflexible project structure lead to time-consuming, expensive and late adaptations. Local optimisation and deviations from the overall objectives are consequences of insufficient synchronisation and coordination. The approach proposed in this paper strives for a paradigm shift from consecutive processes to a modular, parallel approach, which can be reconfigured according to the specific conditions of the planning project and enterprise. This new approach integrates the modularisation and configuration of the planning process as well as aspects of management of instability and second order observation. It has been successfully employed in industry cases, which will be introduced in this paper.