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

3rd International Workshop on Physics-based Models and Experimental Verification - Book of Abstracts

This report contains the abstracts of keynote lectures, oral and Poster presentations at the 3nd International Workshop on Physics Based Modelling of Material Properties and Experimental Observations, with special focus on creep and plastic in metallic materials. The workshop was organized in the context of European Commission’s Enlargement and Integration Action by the Joint Research Centre in collaboration with University of Oxford, Middle East Technical University and Max Planck Institute, June 2- 4, 2014 in Çeşme Turkey. By "physics-based" we refer to models that address microstructures and associated thermodynamic non-equilibrium mechanisms and processes at different length and time scales. Such models include molecular dynamics, dislocation dynamics and crystal plasticity. The ultimate goal is to combine several models into a multi-scale approach to address complex material properties and also application to industrial components. The workshop presentations give an overview of different physics-based models and associated experiments. It provides examples of how such can be used for improved understanding and more reliable predictions but also discussed the limitations and future research needs.JRC.F.4 - Innovative Technologies for Nuclear Reactor Safet

Gold alloys: study of the microstructural, mechanical characteristics and final optimization of production parameters for the realization of full and cable pipe chains

The gold market is one of the major world markets and the Italian companies place the country as one of the major players in this sector. However, the production in these companies is mostly based on the use of artisan skills, without investing in research and studies about the production processes of these materials. In fact, often the process depends on a "craft" way of working, in which the technical and scientific knowledge are dictated more by experience than by a systematic scientific approach. The international bibliography regarding the world of machining of gold alloys is not as developed as in the case of other metal alloys (steels and aluminum alloys), in which the aesthetic appearance is much less important than the functional aspect. The increase in the nationally and internationally competitiveness caused a growing interest to the study of these materials and their metallurgical properties, with the need to create more complex products that are able to maintaining their extremely high quality. Many of the metallurgical concepts of other materials (in particular face-centered cubic structure alloys) can be applied to gold alloys. However, the greatest variety in composition, the well-defined standards in form, the mechanical and aesthetic properties that they have to satisfy, made necessary the knowledge of mode and characteristics, with which the different constituents influencing the machining, heat treatments and the final quality of the semi-finished product. In the first part of the thesis, the main properties of pure gold and gold alloys will be presented, with a particular attention to the main jewelry production technologies and the main usage of gold in the world market. In first chapter the supply, demand and pricing of gold will be generally described to allow an easy collocation of the information contained and the results explained in this thesis, in a larger context such as the world gold market. After, in chapter 2, will be described the main features of gold, which make its the most important metal used for the production of precious artifacts. The attention will be focused mainly on the electronic configuration of gold, and on the physical, optical, and crystallographic properties that result from this. In chapter 3, the aim is to introduce the metallurgical principles of alloying for improve particular properties, such as strengthening, or for adjust other characteristics of gold alloys in order to meet certain requirements. Will be introduced the industrial operations of casting, deformation, heat treatment, and interesting using of innovative approaches to the goldsmith production. Chapter 4 is an overview of the main technologies used in gold jewelry manufacture, the aim is to give a more complete idea of the means of the term “jewelry”, and of the key role of a scientific approach, or the scientific research, focused to improve and develop the industrial production system. The second part of this thesis summarizes the work carried out during the three-year Ph.D in Industrial Engineering. The objectives of the project are the determination of the relationships between the composition and different properties of the gold alloys (the caratage, the color, the mechanical properties,…) used by the goldsmith company in the different stage of the production cycle for the realization of full pipe and cable chain. In particular will be studied the effect of the various constituents and their quantity in the alloys, the mechanical properties and the weldability of these. The investigation will be performed from the melting process, through different plastic deformation and annealing steps, until the realization of the welded semi-finished product. A further objective of the project is the study of the mechanisms of plastic deformation of the different alloys used in the company, in order to optimize the processes of deformation and heat treatments depending on the material used, the various alloying elements and the different production cycles. In chapter 5, will be briefly described the experimental apparatus used for the characterization of the samples (taken from the whole production process in the goldsmith company FilK S.p.A.), in the laboratories of the Department of Industrial Engineering of the Padua University. In chapter 6, will be described the production cycle of the gold welding wires used to solder the hollow gold chain produced. The effect of the microstructure and residual stresses on the corrosion and mechanical properties will be discussed. The study will focus on the control of production parameters in order to improve machinability of the gold wires and to increase their properties. In chapter 7, a statistic analysis of some mechanical and compositional characteristics of gold alloy wires will be reported. The purpose is to individuate an approximation of the possible existing influences and relationships between these and the energy absorbed during deformation. The properties that will be investigated are elongation, Young modulus, ultimate strength and the concentration of gold. In Chapter 8, the production processes of gold alloys plates will be described. The aim of this part of thesis is to optimize the microstructure and the mechanical properties of the products, which, successively, will be welded to an iron sheet to create the base for the final hollow chain products. The parameters of production cycles and the intrinsic properties of the different gold alloys will be studied, with particular attention to the stresses and the microstructures generated from the subsequent deformation and annealing steps. Finally, in chapter 9 the plating process will be analyzed, in order to define the influence of the process parameters on the characteristics of the semi-finished products. Furthermore, different ageing treatments for various gold alloy compositions will be described, the results will allow to optimize time and temperature of the age-hardening treatments for the company’s gold alloys. The whole production tests were performed, in collaboration with Ing. Fabrizio Furlan, in Filk S.p.A., the goldsmith company partner of this collaboration and unique supplier of the material for this research. The main part of the characterization of the different gold samples was carried out at the metallurgy laboratories in the Department of Industrial Engineering, University of Padua, under the supervision of prof. Manuele Dabalà and in collaboration with Ing. Luca Pezzato. Some analyzes, especially the chemical etching of the specimens with different solutions of cyanides, have been performed at other structure: in the laboratories of Progold S.p.A. in collaboration with Ing. Daniele Maggian, Dr. Patrizio Sbornicchia and Dr. Valerio Doppio. The obtained results allowed improving the workability of the gold alloys used by the company with a reduction of the industrial wastes. The optimization of the production parameters, in the different processes, allowed to increase the microstructural quality of the semi-finished products with an improvement on the mechanical and metallurgical characteristics. A suitable control on the production processes and, the optimization of the gold alloy’s compositions, allowed to increase the constancy, the reproducibility of the results and the quality in the production of hollow and cable pipe chains. The obtained results also have a scientific relevance that have allowed their presentation in numerous national and international conferences and publication in scientific journals as reported at the end of the thesis

MATERIALS IN RESTORATIVE DENTISTRY

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73465/1/j.1749-6632.1968.tb20274.x.pd