There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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

A review of dynamic recrystallization phenomena in metallic materials

The double-edge effect of second-phase particles on the recrystallization behaviour and associated mechanical properties of metallic materials

Properties and Application of Geopolymers Vol. 841 (/MSF.841 /book) Development and Investigation of Materials Using Modern Techniques Vol. 840 (/MSF.840/book) Superplasticity in Advanced Materials ICSAM 2015 Vols. 838-839 (/MSF.838-839/book) 12th International Conference on High Speed Machining Vols. 836-837 (/MSF.836-837/book) Sintering Fundamentals II Vol. 835 (/MSF.835/book) Advanced Machining Technologies: Traditions and Innovations Vol. 834 (/MSF.834/book) Applied Materials and Technologies Vol. 833 (/MSF.833/book) Emerging Functional Materials: Book (/MSF.841/book) Papers (/MSF.841)

Materials Science Forum

Modelling the kinetics of strain induced precipitation in Nb-microalloyed steels

This work describes the effect of temperature on both the microstructure and composition of microalloyed steel austenite in the as-reheated condition. Four laboratory steels of similar C levels were analyzed in this investigation. Three steels had different Nb concentrations at con-stant N levels, and the fourth exhibited a difference in N concentration. The average prior-austenite grain size was determined using quantitative metallographic techniques as a function of reheat temperature. The corresponding amount of Nb in solution in austenite was determined from atom probe analysis. Results from this investigation indicate that at elevated temperatures, representative of typical reheating practice, a smaller amount of Nb is soluble in austenite than what would have been predicted from any existing solubility relation for NbCx in austenite. The solubility of Nb and C in austenite for the low-N steels is described by the relation: Log [Nb][C] = 2.06 - 6700/T. Additionally, it is shown that undissolved NbCx particles are present in austenite approximately 125 ‡C above the grain-coarsening temperature.

Compositional and microstructural changes which attend reheating and grain coarsening in steels containing niobium

Precipitation of NbC in a model austenitic steel

This work describes the effect of Nb supersaturation in austenite, as it applies to the strain-induced precipitation potential of Nb(CN), on the suppression of the static recrystallization of austenite during an isothermal holding period following deformation. Four low carbon steels, microalloyed with Nb, were used in this investigation. Three of the steels had variations in Nb levels at constant C and N concentrations. Two steels had different N levels at constant C and Nb concentrations. The results from the isothermal deformation experiments and the subsequent measurement of the solution behavior of Nb in austenite show that the recrystallization-stop temperature (TRXN) increases with increasing Nb supersaturation in austenite. Quantitative transmission electron microscopy analysis revealed that the volume fraction of Nb(CN) at austenite grain boundaries or subgrain boundaries was 1.5 to 2 times larger than Nb(CN) volume fractions found within the grain interiors. This high, localized volume fraction of Nb(CN) subsequently led to high values for the precipitate pinning force (FPIN). These values forFPIN were much higher than what would have been predicted from equilibrium thermodynamics describing the solution behavior of Nb in austenite.

Eric J. Palmiere

Papers

Modelling the kinetics of strain induced precipitation in Nb-microalloyed steels

Compositional and microstructural changes which attend reheating and grain coarsening in steels containing niobium

Precipitation of NbC in a model austenitic steel

The influence of niobium supersaturation in austenite on the static recrystallization behavior of low carbon microalloyed steels

Dissolution and precipitation behaviour in steels microalloyed with niobium during thermomechanical processing