Overview of Tiber-II—Evolution toward an Engineering Test Reactor

TIBER II is designed to be a minimum size and cost candidate for an international Engineering Test Reactor. High-current density Nb₃Sn superconducting magnets with radiation-tolerant polymide insulation is combined with a minimum thickness tungsten inbored shield and a common, external vacuum boundary to minimize the inner radial build of the tokamak core. This results in a major radius of 3 m, compared to 5 m for previous ETR designs such as INTOR, with correspondingly lower costs expected. Cyclic stress fatigue limits the number of pulses so that steady-state current drive, based on a combination of neutral beams, lower hybrid and ECH, is designed to achieve reactor-relevant nuclear testing conditions (Fluence 3MW yr/m², rwall > 1 MW/m² in steady state).This report is abstracted from a more complete information document UCID-20863 with numerous authors. See Ref. l for complete credits.     

Tri-Reforming of Methane over NdM0.25Ni0.75O3 (M = Cr,Fe) Catalysts and the Effect of CO2 Composition

Catalysis Letters - The NdM0.25Ni0.75O3 (M?=?Cr, Fe) named NCN and NFN catalysts precursors were synthesized and characterized. The CO2 utilization in the feed was studied in the...     

Modulation on the electrical and optical properties of Na and Rh co-doped Ruddlesden-Popper layered Ca3Ti2O7

Layered perovskite Ca_2.91Na_0.09Ti_2-xRh_xO₇ (x?=?0.00, 0.02, 0.04, 0.06) were synthesized by a conventional solid-state reaction. Room temperature ferroelectricity has been confirmed. The remanent polarization increases with an increase of Rh content, which is due to a larger oxygen octahedral distortion by Rh doping. The coercive field increases with Rh doping as the pinning effect of oxygen vacancies reduce the mobility of domain wall. Remanent polarization and coercive field are caused by different mechanisms, so it is possible to modulate them independently to meet the requirement of application in ferroelectric field. The concentration of oxygen vacancy increased with Rh doping, leading to the significant increase of leakage current density. The bandgap of samples doped with Rh drastically decrease and the visible light response of the sample was improved by Rh doping due to the formation of impurity energy levels within the band gap.

     

Phase diagram and electrical behavior of silicon-rich iridium silicide compounds

The iridium-silicon phase diagram on the silicon-rich side was investigated by means of X-ray powder diffraction, density, differential thermal analysis (DTA), metallography, microprobe analysis, and electrical resistivity. Attempts were made to prepare eight previously reported silicon-rich iridium silicide compounds by arc melting and Bridgman-like growth. However, microprobe analysis identified only five distinct compositions: IrSi, Ir₄Si₅, Ir₃Si₄, Ir₃Si₅ and IrSi_≈3. The existence of Ir₂Si₃, Ir₄Si₇, and IrSi₂ could not be confirmed in this study. DTA in conjunction with X-ray powder diffraction confirm polymorphism in IrSi_≈3, determined to have orthorhombic and monoclinic unit cells in the high and low temperature forms. A eutectic composition alloy of 80.5 ± 1 at.% Si was observed between IrSi_≈3 and silicon. Both Ir₄Si₅ and Ir₃Si₄ exhibit distinct metallic behavior while Ir₃Si₅ is semiconducting. IrSi and IrSi_≈3 exhibit nearly temperature-independent electrical resistivities on the order of (5–10) × 10⁻⁶ ω m.     

In Situ Investigation of TCP Phase Formation,Stress Relaxation and γ/γ′ Lattice Misfit Evolution in Fourth Generation Single Crystal Ni-Base Superalloys by X-Ray High Temperature Diffraction

Metallurgical and Materials Transactions A - In nickel-based superalloys, the lattice misfit between the γ and γ′ phases and the propensity to TCP phase formation at service...     

Development of Cr and Al Pack Cementation Coatings on Co-Based γ/γ′ Superalloys

Metallurgical and Materials Transactions A - Co-based superalloys have been developed as candidate materials to replace Ni-based superalloys in hot sections of turbine engines, however, their...     

A Heat Treatment to Produce a Coarse-α-Particle Size in Ti–6Al–4V

Metallurgical and Materials Transactions A - A heat-treatment method to develop a coarse-α-particle size in Ti–6Al–4V with a fully-globular (equiaxed) microstructure was developed....     

The Fe-Ni (iron-nickel) system

The online version of the original article can be found at     

The assessment of thermal history in pressure vessel steel

A component of the present work involves attempts to simulate the microstructures of 1Cr-0.5Mo steel sample removed from service after extended exposure to elevated temperatures (10⁵ h at 535°C). The aim is to establish a basis for assessing the thermal history of service components and service weldments. Previous work has established that it is not possible to adequately simulate service microstructures using accelerated isothermal heat treatments alone. A selective mechanical testing program at elevated temperature has thus been investigated to superimpose the effect of stress on heat treatment. Qualitative comparison within each of these sets of micrographs suggests that the intraferritic precipitation in the creep samples is in each case refined and of a higher density compared to the sample subjected to isothermal heat treatments. It has been suggested that a comparison of the composition of the pearlitic M₃C in creep test samples with the empirical relationship may provide a means of assessing the average thermal history of the ex-service sample.