EVIDENCE FOR TWO TELLURIUM SITES IN DILUTE LIQUID Te-Tl ALLOYS.

Recently, experimental evidence was presented which suggests that as the stoichiometric composition CuTe, NiTe, Tl//2Te and MnTe are approached from pure Te in the liquid state, substantial charge transfer takes place and Te exists in the form Te**y**31 ions with y close to 2. The system studied (Te-Tl) is one in which charge transfer localizes electrons on the tellurium and leads to semiconducting behavior at the stoichiometric composition Tl//2Te.

Thin film shape memory alloys for optical sensing applications

Based on shape memory effect of the sputtered thin film shape memory alloys, different types of micromirror structures were designed and fabricated for optical sensing application. Using surface micromachining, TiNi membrane mirror structure has been fabricated, which can be actuated based on intrinsic two-way shape memory effect of the free-standing TiNi film. Using bulk micromachining, TiNi/Si and TiNi/Si 3N 4microcantilever mirror structures were fabricated. © 2007 IOP Publishing Ltd.

Thin film shape memory alloys and microactuators

For Micro-electro-mechanical System (MEMS) applications, TiNi-based thin film Shape Memory Alloys (SMAs) possess many desirable properties, such as high power density, large transformation stress and strain upon heating and cooling, superelasticity and biocompatibility. In this paper, recent development in TiNi-based thin film SMA and microactuator applications is discussed. The topics related to film deposition and characterisation is mainly focused on crystal nucleation and growth during annealing, film thickness effect, film texture, stress induced surface relief, wrinkling and trenches as well as Temperature Memory Effect (TME). The microactuator applications are mainly focused on microvalve and microcage for biological applications, micromirror for optical applications and data storage using nanoindentation method. Copyright © 2009, Inderscience Publishers.

Supersonic laser deposition of Ti and Ti64 alloys

The importance of metal coating technologies drives the continuous improvement of metal deposition techniques for application in a wide range of industrial sectors. This work presents the foundations of a new process technology for the deposition of Ti and Ti64 coatings on various substrates using supersonic powder streams and impact site laser heating. Full density metallic deposits are obtained under appropriate impact conditions without the need for transiting the melting point of the deposited material or substrate leading to large energy savings. Details of the experimental approach will be presented along with the general characteristics of the titanium coatings produced using this novel coatings method.

Copper-nickel alloys for marine aquacultural engineering

Engineering developments, problems of marine corrosion, fouling and practical innovative applications of copper-nickel alloys in comparison with other materials for marine aquacultural engineering are presented. Coefficient of drag and hydrodynamic force acting on nylon and polyethylene net enclosures have shown a four-fold increase of force in four months at the Cochin harbour due to fouling. Corrosion behaviour of copper-nickel and other copper base alloys are also presented. Effects of copper additions to culture water are reviewed.

Relaxation and fracture characteristics in Co-based amorphous alloys

In this article a study of the fracture characteristics of Co66Fe4Mo2Si16B12 amorphous ribbon in the as-quenched state and after relaxation is presented. In the as-quenched state, the morphology of the crack surface shows a 'vein pattern' structure that corresponds to a large amount of plastic flow. After relaxation the surface morphology of the crack shows that when the temperature of the thermal annealing increases the plastic flow involved in the crack decreases. In the as-quenched state dynamic fracture characteristics (crack branching and stress wave induced crack) have been observed. These dynamic characteristics have not been observed in the relaxed samples but in the samples annealed at 250 °C for 20 min apart from the main crack, a crack along the width of the ribbon has been observed. © 2006 Elsevier B.V. All rights reserved.

Plastic deformation of metals and alloys

This chapter focuses on relationships between plastic deformation structures and mechanical properties in metals and alloys deforming by dislocation glide. We start by summarizing plastic deformation processes, then look at the fundamental mechanisms of plastic deformation and explore how deformation structures evolve. We then turn to experimental techniques for characterization which have allowed deformation microstructures to be quantified in terms of common structural parameters. The microstructural evolution has been described over many length scales and analyzed theoretically based on general principles. The deformation microstructures are related to work hardening stages. Finally we identify correlations between a wide range of microstructural features and mechanical properties, particularly flow stress, and use experimental observations to illustrate their inter-relationships.