Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

1. Introduction 2. The physical metallurgy of nickel and its alloys 3. Single crystal superalloys for blade applications 4. Superalloys for turbine disc applications 5. Environmental degradation: the role of coatings 6. Summary and future trends.

The Superalloys: Fundamentals and Applications

Alloying has long been used to confer desirable properties to materials. Typically, it involves the addition of relatively small amounts of secondary elements to a primary element. For the past decade and a half, however, a new alloying strategy that involves the combination of multiple principal elements in high concentrations to create new materials called high-entropy alloys has been in vogue. The multi-dimensional compositional space that can be tackled with this approach is practically limitless, and only tiny regions have been investigated so far. Nevertheless, a few high-entropy alloys have already been shown to possess exceptional properties, exceeding those of conventional alloys, and other outstanding high-entropy alloys are likely to be discovered in the future. Here, we review recent progress in understanding the salient features of high-entropy alloys. Model alloys whose behaviour has been carefully investigated are highlighted and their fundamental properties and underlying elementary mechanisms discussed. We also address the vast compositional space that remains to be explored and outline fruitful ways to identify regions within this space where high-entropy alloys with potentially interesting properties may be lurking. High-entropy alloys have greatly expanded the compositional space for alloy design. In this Review, the authors discuss model high-entropy alloys with interesting properties, the physical mechanisms responsible for their behaviour and fruitful ways to probe and discover new materials in the vast compositional space that remains to be explored.

High-entropy alloys

High entropy alloys: A focused review of mechanical properties and deformation mechanisms

During the past decade considerable research efforts have been directed towards achieving balanced engineering properties of two-phase γ-titanium aluminide alloys for future applications as structural materials. For optimization of mechanical properties such as yield and creep strengths, tensile ductility and fracture resistance, a basic understanding of the temperature dependent micromechanisms of plasticity and fracture, and their interplay with various microstructural constituents is required. In this review article, the current knowledge on dislocation types and slip systems, the development of deformation substructures, factors controlling the mobility and multiplication of dislocations, interface related plasticity, solid solution and precipitate strengthening mechanisms as well as microscopic aspects of creep and fracture will be addressed. These topics will be related to specific microstructures and associated engineering properties.

Microstructure and deformation of two-phase γ-titanium aluminides

Cross-slipping process and the stress-orientation dependence in pure copper

A study of cross-slip activation parameters in pure copper

Thermal activation parameters of plastic flow reveal deformation mechanisms in the CrMnFeCoNi high-entropy alloy

Mechanical tests on a polycrystalline γ Ti47A151,Mn2 alloy between ‐ 150 and 1000°C and subsequent microstructure analysis clearly distinguish between three temperature domains which correspond to different deformation mechanisms. At low temperatures, the motion of superdislocations dragging faulted dipoles is rate controlling. At intermediate temperatures where a stress anomaly is observed, screw simple dislocations are observed with cusps, the density of which increases with increasing temperature. A description of the simple dislocation motion based on these observations is developed. The glide of a screw simple dislocation in two planes through a Peierls mechanism is believed to be the intrinsic source for the formation of pinning points. It is proposed that these pinning points can be erased by lateral motion of superkinks: an unzipping process. A model for this pinning-unzipping mechanism will be fully developed in part 11. At high temperatures, the climb of simple dislocations appears to c...

Modelling the flow stress anomaly in γ-TiAl I. Experimental observations of dislocation mechanisms

A new method is presented that allows the measurement of microscopic activation volumes which are typical of thermally activated dislocation processes. It consists of a repeated relaxation test with constant durations, which start at a given stress level. The advantages of this method, as compared to a previous one which uses constant stress drops, are outlined. The new method is successfully applied to the determination of the transition stress between micro- and macro-plastic deformation in the alloy Ni 3 (Al,Hf) at room temperature.

Joël Bonneville

Papers

Cross-slipping process and the stress-orientation dependence in pure copper

A study of cross-slip activation parameters in pure copper

Thermal activation parameters of plastic flow reveal deformation mechanisms in the CrMnFeCoNi high-entropy alloy

Modelling the flow stress anomaly in γ-TiAl I. Experimental observations of dislocation mechanisms

A new method for activation volume measurements: application to Ni3(Al,Hf)