AuCuAl shape memory alloys for use in opto-mechanical nanoactuators

University of Technology, Sydney. Faculty of Science.Shape memory alloys (SMAs) are a remarkable family of metallic materials that have the ability to return to their initial state and shape after being deformed. The key attribute that candidate alloys must possess is the existence of a reversible martensitic phase transformation. The most commonly used SMA, NiTi or ‘Nitinol’, has been proposed for a number of practical and theoretical applications [1-4], however a 100 nm lower limit has been found when producing thin films of this material for nanoscale applications. It has been shown that TiNi films thinner than this lose their shape memory effect due to oxide formation [5]. In the present work I explore whether variations of the Au₇Cu₅Al₄ SMA could be used as an alternate material for nanoscale SMA applications due to the resistance of Au₇Cu₅Al₄ to both aging [6] and oxidation [7]. A bonus is that the high Au content of this alloy may allow it to support a surface plasmon resonance in the visible part of the electromagnetic spectrum. My project involved the investigation of both bulk and thin-film samples. A range of techniques were used to examine the properties of both the bulk and thin-film alloys including SEM, TEM, EDS, SIMS, powder diffraction (X-ray and neutron), thermal analysis, electrical resistance and spectrophotometry. Various types of mathematical modelling were then used to interpret the results as well as to simulate the operation of hypothetical devices made with this alloy. Bulk AuCuAl SMAs with Al content varying along the Au 85 wt.% Au line of the AuCuAl ternary diagram were produced and their microstructures, physical properties and phase transformations studied. The extent to which the prototypical Au₇Cu₅Al₄ alloy resisted aging was investigated and the mechanisms that lead to some small changes in the transformation temperature under particular circumstances were considered. Whilst these alloys are very resistant to aging at high temperatures, aging below approximately 140°C in the austenite phase field results in a surprising and significant drop in the subsequent martensite-to-austenite transformation temperature. Nanoscale films of AuCuAl with similar compositions to those of the bulk alloys were then synthesised. The phase transformation characteristics in these samples were also determined and found to be sensitive to the Al content and deposition conditions. The sub-100 nm-thick films were produced following the same compositional trend as the bulk ternary samples, producing a sequence of α-, β- and γ-structured films as the Al content was systematically increased. It is shown that, when deposited under the right conditions and with the correct compositions, AuCuAl films could be produced with the ability to undergo a reversible austenite/martensite phase transformation. Reflection and transmission spectra of these films were measured and used to calculate their dielectric function (complex refractive index). These data were in turn used to model the localised surface plasmon resonances in hypothetical, opto-mechanical nano-actuators made from Au₇Cu₅Al₄. The calculations predict that the extinction of light of a wavelength of 740 nm could be modulated by a factor of 26 times by a suitably designed, SMA actuator. This project has paved the way for the possible future fabrication and testing of new opto-mechanical devices based on these principles

The aluminium-copper-gold ternary system

Despite Au, Al and Cu being individually very well-known elements, their ternary phase diagram has not been studied in as much detail as those of many other Au-containing ternaries. Here we review what is known, and consider the prospects for technological exploitation of some of the ternary compositions. The components of greatest interest in Al-Au-Cu may be the β-phases, at least two of which have shape memory properties. Of these, 'Spangold', which has the nominal stoichiometry Au7Cu5Al4, has received some attention for jewellery applications, while the edge compound Cu3Al is a well-known shape memory composition with corresponding specialised industrial uses. The properties of other β-phase compositions in the system have been scarcely investigated. The system also contains an extensive γ-phase, Al4AuxCu9-x, where x ranges from 0 to ~6.5, and the purple gold phase AuAl2

Paving the way for research findings: writers' rhetorical choices in education and applied linguistics

Notwithstanding the existence of previous investigations into how research results are presented in different academic disciplines, fewer studies have looked into how authors pave the way for their results, the interdisciplinary differences in ‘result pavements’, and the interconnections between their communicative functions and linguistic choices. Using the techniques of genre analysis, I have analyzed two corpora of research reports in applied linguistics and education in order to identify the possible ways in which experienced writers schematically pave the way for their findings. Using evidence based on authentic research articles, this study demonstrates how writers set the stage for their research results by (i) demonstrating their control of the structure and flow of result-related information, (ii) connecting past research with a current finding while furnishing pertinent background elements that lead the readership progressively to specific findings, (iii) regenerating readers’ interest in their initial research purposes, and (iv) deploying locatives to embed results in a ‘space-saving strategy’ aimed at presenting an abridged Results section. I have also analyzed interdisciplinary differences in the frequencies of these rhetorical steps and the range of intricate linguistic mechanisms employed by authors as communicative resources in each step to establish a smooth rhetorical transition that sets the stage for their research results

Research Methodologies and Business Discourse Teaching

This chapter will:; ; ; Define English for specific purposes and indicate the specific ways in which it has been influential on business discourse teaching;; ; ; Discuss the most relevant approaches to genre analysis that have been used in business discourse teaching;; ; ; Explore the most relevant approaches to critical discourse analysis and organizational rhetoric for business discourse teaching;; ; ; Identify the most relevant aspects of multimodal discourse analysis for business discourse teaching;; ; ; Provide a case study that illustrates the use of one approach to business discourse teaching, showing how practitioners can incorporate it into their classroom- or consultancy-based ideas

Research and Client-Based Projects

This chapter will:; ; ; Show how to develop a needs analysis based on sound research principles;; ; ; Examine a number of different client-based projects that have taken a business discourse approach to teaching;; ; ; Discuss different ways in which business discourse research can be used in the classroom;; ; ; Present a case study that illustrates how business discourse projects can be incorporated into teaching practices together with a set of tasks related to the use of business discourse research in the classroom and a set of further readings

Utilization of Renewable Biomass and Waste Materials for Production of Environmentally-Friendly, Bio-based Composites

The introduction of renewable biomass into a polymer matrix is an option competing with other possibilities, such as energy recovery and/or re-use in the carbonized state, or production of chemicals, such as, in the case of ligno-cellulosic waste, concentrates on the production of simple sugars, then possibly leading to the development of biopolymers. These competitive applications have also some interest and market, however with a considerable energy, water and materials consumption, due also to the not always high yielding. Other possibilities for renewable biomass are therefore being used as fillers to increase mechanical performance of polymers or to allow e.g., the absorption of toxic chemicals. This review concentrates on the use of biomass as close as possible to the “as received” state, therefore avoiding whenever suitable any thermal treatment. More specifically, it focuses on its introduction into the three categories of oil-based (or bio-based replacement) of engineered polymers, into industrial biopolymers, such as poly(lactic acid) (PLA) and self-developed biopolymers, such as thermoplastic starch (TPS)

Connected parents: combining online and off-line parenthood in vlogs and blogs

This article explores evaluative discourse in a corpus sample of parents' vlogs (video blogs) and blogs (henceforth v/ blogs) dealing with family tasks and responsibilities, as a reflection of underlying values concerning parenthood. It pays special attention to the important role played by the expression of attitude, understood as "ways of feeling" and including the meanings of affect, judgement and appreciation, together with positive politeness in the social practices of the discursive construction of online and off-line parenthood. Analysis and description of the data show two main patterns in parents' practices, either aiming at perfection through juggling and multi-tasking or building resistance to the demands of families and society. Results show that parents frequently exploit the system of affect for building positive face and rapport, while indirectly expressing judgement of social esteem and social sanction, which construct their identities as mothers and fathers and those of the members of their communities of practice. The corpus for the study consists of a random sample of 400 evaluative units in posts and comments on v/ blogs dealing with family tasks and responsibilities (200 in English and 200 in Spanish, with half the sample being drawn from fathers' and the other half from mothers' v/ blogs). I will approach the analysis of the data from appraisal (Martin and White 2005, Bednarek 2008) and politeness theory (Brown and Levinson 1987) in order to explore the features of evaluative discourse and the management of face. The methodology for processing the data borrows quantitative techniques from Corpus Linguistics, including the coding and statistical treatment of the sample with UAM Corpus Tools (O'Donnell 2011), together with Pragmatics and Discourse Analysis (DA), as done in some previous research (Santamaría-García 2011, 2014).Project "EMO-FUNDETT: EMOtion and language at work", I+D FFI2013-47792-C2-1-P, sponsored by the Spanish Ministry of Science and Innovatio

Understanding Communication of Sustainability Reporting: Application of Symbolic Convergence Theory (SCT)

The purpose of this paper is to investigate the nature of rhetoric and rhetorical strategies that are implicit in the standalone sustainability reporting of the top 24 companies of the Fortune 500 Global. We adopt Bormann’s (Q J Speech 58(4):396–407, 1972) SCT framework to study the rhetorical situation and how corporate sustainability reporting (CSR) messages can be communicated to the audience (public). The SCT concepts in the sustainability reporting’s communication are subject to different types of legitimacy strategies that are used by corporations as a validity and legitimacy claim in the reports. A content analysis has been conducted and structural coding schemes have been developed based on the literature. The schemes are applied to the SCT model which recognizes the symbolic convergent processes of fantasy among communicators in a Society. The study reveals that most of the sample companies communicate fantasy type and rhetorical vision in their corporate sustainability reporting. However, the disclosure or messages are different across locations and other taxonomies of the SCT framework. This study contributes to the current CSR literature about how symbolic or fantasy understandings can be interpreted by the users. It also discusses the persuasion styles that are adopted by the companies for communication purposes. This study is the theoretical extension of the SCT. Researchers may be interested in further investigating other online communication paths, such as human rights reports and director’s reports