Central Queensland Mining Supplies Pty Ltd v Columbia Steel Casting Co Ltd

In Central Queensland Mining Supplies Pty Ltd v Columbia Steel Casting Co Ltd [2011] QSC 183 Applegarth J considered complaints made by the defendant about the approach the plaintiff had taken in its endeavour to comply with its disclosure obligation under r 211 of the Uniform Civil Procedure Rules 1999 (Qld). The judgment also provides an indication of the direction the court is taking in relation to disclosure and document management in matters involving large numbers of documents.

Compressive behaviour of nanocrystalline Mg-5Al alloys

Magnesium alloys are attracting increasing research interests due to their low density, high specific strength, good machinability and availability as compared to other structural materials. However, the deformation and failure mechanisms of nanocrystalline (nc) Mg alloys have not been well understood. In this work, the deformation behaviour of nc Mg-5Al alloys was investigated using compression test, with focus on the effects of grain size. The average grain size of the Mg- Al alloy was changed from 13 to 50 nm via mechanical milling. The results showed that grain size had a significant influence on the yield stress and ductility of the Mg alloys, and the materials exhibited increased strain rate sensitivity with a decrease in grain size. The deformation mechanisms were also strongly dependent on the grain sizes.

Supramolecular selection in molecular alloys

Complexes of the type \[M(phen)3](PF6)2 (M = Ni(II), Fe(II), Ru(II) and phen = 1,10-phenanthroline) were found to co-crystallize to form molecular alloys (solid solutions of molecules) with general formula \[MAxMB1–x(phen)3](PF6)2·0.5H2O in which the relative concentrations of the metal complexes in the crystals closely match those in the crystallizing solution. Consequently, the composition of the co-crystals can be accurately predicted and controlled by modulating the relative concentrations of the metal complexes in the crystallizing solution. Although they are chemically and structurally similar, complexes of the type \[M(bipy)3](PF6)2 (M = Ni(II), Fe(II), Ru(II) and bipy = 2,2′-bipyridine) display markedly different behavior upon co-crystallization. In this case, the resulting co-crystals of general formula \[MAxMB1–x(bipy)3](PF6)2 have relative concentrations of the constituent complexes that are markedly different from the relative concentrations of the complexes initially present in the crystallizing solution. For example, when the nickel and iron complexes are co-crystallized from a solution containing a 50:50 ratio of each, the result is the formation of some crystals with a higher proportion of iron and others with a higher proportion of nickel. The relative concentrations of the metal complexes in the crystals can vary from those in the crystallizing solutions by as much as 15%. This result was observed for a range of combinations of metal complexes (Ni/Fe, Ni/Ru, and Fe/Ru) and a range of starting concentrations in the crystallizing solutions (90:10 through to 10:90 in 10% increments). To explain this remarkable result, we introduce the concept of “supramolecular selection”, which is a process driven by molecular recognition that leads to the partially selective aggregation of like molecules during crystallization.

Progress towards slip-casting YBa2Cu3O7-x monoliths

Sintered bars of YBa2Cu3O7-x obtained by slip-casting are investigated for drying and sintering behaviour. High J(cm) values (approximate to 10(6) A/cm(2) at 77K) are obtained, although J(ct) values are low (approximate to 10(2) A/cm(2) at 77K). Microstructural characterisation is undertaken on selected samples which demonstrate significant differences in physical density and critical current density.

Shape-formed ceramic superconductors by slip-casting

In order to rigorously test emerging applications using prototypes and pilot designs, high temperature superconductor (HTS) materials must be fabricated into a variety of shapes in an economical manner. We have developed a simple, economical, ceramic slip-casting approach to form complex shaped monolithic HTS articles for which high bulk density has been achieved. The sintered articles exhibit good Meissner signal and consist of phase-pure HTSC phase. A low transport critical current density is observed and is explained on the basis of densification and grain growth. © 1995 The Metallurgical of Society of AIME.

Deformation behaviour of nanocrystalline Mg-AI alloys during nanoindentation

The deformation behaviour of Mg-5%AI alloys and its dependence with gain size and strain rate were investigated using nanoindentation. The grain sizes were successfully reduced below 100 nm via mechanical alloying method. It was found that the strain rate sensitivity increased with decreasing grain size. The smaller activation volumes and the plastic deformation mechanisms involving grain boundary activities are considered to contribute to the increase of strain rate sensitivity in the nanocrystalline alloys.

A facile chemical screening method for the detection of stress corrosion cracking in 9 carat gold alloys

Stress corrosion cracking (SCC) is a well known form of environmental attack in low carat gold jewellery. It is desirable to have a quick, easy and cost effective way to detect SCC in alloys and prevent them from being used and later failing in their application. A facile chemical method to investigate SCC of 9 carat gold alloys is demonstrated. It involves a simple application of tensile stress to a wire sample in a corrosive environment such as 1–10 % FeCl3 which induces failure in less than 5 minutes. In this study three quaternary (Au, Ag, Cu and Zn) 9 carat gold alloy compositions were investigated for their resistance to SCC and the relationship between time to failure and processing conditions is studied. It is envisaged that the use of such a rapid and facile screening procedure at the production stage may readily identify alloy treatments that produce jewellery that will be susceptible to SCC in its lifetime.

The electrochemical corrosion behaviour of quaternary gold alloys when exposed to 3.5% NaCl solution

Lower carat gold alloys, specifically 9 carat gold alloys, containing less than 40 % gold, and alloying additions of silver, copper and zinc, are commonly used in many jewellery applications, to offset high costs and poor mechanical properties associated with pure gold. While gold is considered to be chemically inert, the presence of active alloying additions raises concerns about certain forms of corrosion, particularly selective dissolution of these alloys. The purpose of this study was to systematically study the corrosion behaviour of a series of quaternary gold–silver–copper–zinc alloys using dc potentiodynamic scanning in saline (3.5 % NaCl) environment. Full anodic/cathodic scans were conducted to determine the overall corrosion characteristics of the alloy, followed by selective anodic scans and subsequent morphological and compositional analysis of the alloy surface and corroding media to determine the extent of selective dissolution. Varying degrees of selective dissolution and associated corrosion rates were observed after anodic polarisation in 3.5 % NaCl, depending on the alloy composition. The corrosion behaviour of the alloys was determined by the extent of anodic reactions which induce (1) formation of oxide scales on the alloy surface and or (2) dissolution of Zn and Cu species. In general, the improved corrosion characteristics of alloy #3 was attributed to the composition of Zn/Cu in the alloy and thus favourable microstructure promoting the formation of protective oxide/chloride scales and reducing the extent of Cu and Zn dissolution.

Investigation on mechanical behaviour of AM60 magnesium alloys

Purpose: In this work, tension, impact, bend and fatigue tests were conducted in an AM60 magnesium alloy. The effects of environmental temperature and loading rates on impact and tension behavior of the alloy were also investigated. Design/methodology/approach: The tests were conducted using an Instron universal testing machine. The loading speed was changed from 1 mm/min to 300 mm/min to gain a better understanding of the effect of strain rate. To understand the failure behavior of this alloy at different environmental temperatures, Charpy impact test was conducted in a range of temperatures (-40~35°C). Plane strain fracture toughness (KIC) was evaluated using compact tension (CT) specimen. To gain a better understanding of the failure mechanisms, all fracture surfaces were observed using scanning electron microscopy (SEM). In addition, fatigue behavior of this alloy was estimated using tension test under tension-tension condition at 30 Hz. The stress amplitude was selected in the range of 20~50 MPa to obtain the S-N curve. Findings: The tensile test indicated that the mechanical properties were not sensitive to the strain rates applied (3.3x10-4~0.1) and the plastic deformation was dominated by twining mediated slip. The impact energy is not sensitive to the environmental temperature. The plane strain fracture toughness and fatigue limit were evaluated and the average values were 7.6 MPa.m1/2 and 25 MPa, respectively. Practical implications: Tested materials AM60 Mg alloy can be applied among others in automotive industry aerospace, communication and computer industry. Originality/value: Many investigations have been conducted to develop new Mg alloys with improved stiffness and ductility. On the other hand, relatively less attention has been paid to the failure mechanisms of Mg alloys, such as brittle fracture and fatigue, subjected to different environmental or loading conditions. In this work, tension, impact, bend and fatigue tests were conducted in an AM60 magnesium alloy.

Nanostructured high strength Mg-5%Al-x%Nd alloys prepared by mechanical alloying

Nanostructured high strength Mg-5%Al-x%Nd alloys were prepared by mechanical alloying. Microstructural characterization reveled average crystalline size to be about 30 nm after mechanical alloying while it increased to about 90 nm after sintering and extrusion. Mechanical properties showed increase in 0.2% yield stress, ultimate tensile strength was attributed to reduction in gain size as well as to the enhanced diffusion after mechanical activation. Although ultra high yield stress was observed from the specimen with 5% Nd, its ductility was reduced to about 1.6%.

Fabrication and microstructure of mechanically alloyed Mg-Al-Nd alloys

In this work, nanocrystalline Mg-Al-Nd alloys were fabricated using mechanical alloying method. Phase structure of the extrided rods was examined using X-ray diffraction (XRD) and the microstructures were observed using transmission electronic microscopy (TEM). High yield strength was obtained in the alloys with a high Nd content due to grain refinement and Nd rich precipitate phase.

Telstra on the TV casting couch to trump its telco peers

This week, Telstra announced it will shortly introduce a new streaming video set top box. For a number of reasons, this is a very smart move.

A water model study of the flow asymmetry inside a continuous slab casting mold

The work studies the extent of asymmetric flow in water models of continuous casting molds of two different configurations. In the molds where fluid is discharged through multiple holes at the bottom, the flow pattern in the lower portion depends on the size of the lower two recirculating domains. If they reach the mold bottom, the flow pattern in the lower portion is symmetrical about the central plane; otherwise, it is asymmetrical. On the other hand, in the molds where the fluid is discharged through the entire mold cross section, the flow pattern is always asymmetrical if the aspect ratio is 1:6.25 or more. The fluid jet swirls while emerging through the nozzle. The interaction of the swirling Jets with the wide sidewalls of the mold gives rise to asymmetrical flow inside the mold. In the molds with lower aspect ratios, where the jets do not touch the wide side walls, the flow pattern is symmetrical about the central plane.

Glass forming ability and stability: Ternary Cu bearing Ti, Zr, Hf alloys

Four Cu bearing alloys of nominal composition Zr25Ti25Cu50, Zr34Ti16Cu50, Zr25Hf25Cu50 and Ti25Hf25Cu50 have been rapidly solidified in order to produce ribbons. All the alloys become amorphous after meltspinning. In the Zr34Ti16Cu50 alloy localized precipitation of cF24 Cu5Zr phase can be observed in the amorphous matrix. The alloys show a tendency of phase separation at the initial stages of crystallization. The difference in crystallization behavior of these alloys with Ni bearing ternary alloys can be explained by atomic size, binary heat of mixing and Mendeleev number. It has been observed that both Laves and Anti-Laves phase forming compositions are suitable for glass formation. The structures of the phases, precipitated during rapid solidification and crystallization can be viewed in terms of Bernal deltahedra and Frank-Kasper polyhedra.

Resolidification behaviour of laser surface-melted metals and alloys

The solidification behaviour is described of two pure metals (Bi and Ni) and two eutectic alloys (A1-Ge and AI-Cu) under nonequilibrium conditions, in particular the microsecond pulsed laser surface melting. The resolidification behaviour of bismuth shows that epitaxial regrowth is the dominant mechanism. For mixed grain size, regrowth of larger grains dominates the microstructure and can result in the development of texture. In the case of nickel, epitaxial growth has been noted. For lower energy pulse-melted pool, grain refinement takes place, indicating nucleation of fresh nickel grains. The A1-Ge eutectic alloy indicates the nucleation and columnar growth of a metastable monoclinic phase from the melt-substrate interface at a high power density laser irradiation. An equiaxed microstructure containing the same monoclinic phase is obtained at a lower power density laser irradiation. It is shown that the requirement of solution partition acts as a barrier to eutectic regrowth from the substrate. The laser-melted pool of A1-Cu eutectic alloy includes columnar growth of c~-A1 and 0-A12Cu phase followed by the dendritic growth of A12Cu phase with ct-Al forming at the interdendritic space. In addition, a banded microstructure was observed in the resolidified laser-melted pool.