Mn微合金化对Ti-Al-Mo-Zr-Fe-B合金组织演变和力学性能的影响

通过OM、EBSD和TEM等研究了Mn微合金化对新型近α Ti-Al-Mo-Zr-Fe-B合金微观组织和力学性能的影响。结果表明：添加0.5%（质量分数）的Mn元素可以将合金的铸态微观组织从3.28 μm细化到2.65 μm,使其抗拉伸强度从882 MPa提高到966 MPa,但延伸率从7.8%下降到5.1%。锻造后的2种合金的晶粒尺寸趋于一致,微观组织趋于等轴化且Mn微合金化后的组织更加均匀。锻造后,Ti-Al-Mo-Zr-Fe-B合金的抗拉伸强度和延伸率增加到966 MPa和16.4%,而含有0.5%（质量分数）Mn元素的合金具有更高的抗拉伸强度,达到了1079 MPa,同时延伸率达到了15.8%。结论表明,强度的提高可以归因于Mn元素的固溶强化效应,同时Mn微合金化处理使合金中的Al元素富集于α相,有利于提高合金的强度和塑性。     

Bose–Einstein Condensation in the Pseudogap Phase of Cuprate Superconductors

We have identified the unscreened Fröhlich electron–phonon interaction (EPI) as the most essential for pairing in cuprate superconductors as now confirmed by isotope substitution, recent angle-resolved photoemission (ARPES), and some other experiments. Low-energy physics is that of mobile lattice polarons and bipolarons in the strong EPI regime. Many experimental observations have been predicted or explained in the framework of our “Coulomb–Fröhlich” model, which fully takes into account the long-range Coulomb repulsion and the Fröhlich EPI. They include pseudo-gaps, unusual isotope effects and upper critical fields, the normal state Nernst effect, diamagnetism, the Hall–Lorenz numbers, and a giant proximity effect (GPE). These experiments along with the parameter-free estimates of the Fermi energy and the critical temperature support a genuine Bose–Einstein condensation of real-space lattice bipolarons in the pseudogap phase of cuprates. On the contrary, the phase fluctuation (or vortex) scenario is incompatible with the insulating-like in-plane resistivity and the magnetic-field dependence of orbital magnetization in the resistive state of underdoped cuprates.     

Editorial—Multidisciplinary Design Optimization

Optimization and Engineering -     

Ideal Multi-Component Separating Cascade

Theoretical Foundations of Chemical Engineering - A scheme for calculating a countercurrent cascade is proposed and conservation equations for the concentration and flows in the separation cascade...     

To the theory of underwater ice evolution,or nonlinear dynamics of “false bottoms”

We present a mathematical model describing evolution of false bottoms often met between an under-ice melt pond and the underlying ocean during summer. The model treats a false bottom as the region of mixed phase (mushy layer) whose coordinates depend on time and determine the phase transition area. As the heat and the salt fluxes in the ocean are strongly influenced by turbulence and the ice meltwater accumulating underneath the ice cover is practically fresh, we use modified boundary conditions for heat and mass fluxes at the interfaces of phase transition. Explicit analytical solutions (thickness of false bottom and growth rates of its boundaries, temperature and salinity distributions, solid phase fraction and ocean-to-ice heat flux) of the nonlinear model under consideration are found. Model predictions are in good agreement with existing experimental data and physical concepts of phenomena under study.     

Development and application of amorphous core-distribution transformers in Québec

This paper describes research and development activities at Hydro-Québec over the last ten years for improving the efficiency of distribution transformers in Québec. A shell-type (wound-core) design making optimum use of the properties of amorphous metals (Metglas TCA formerly known as Metglas 2605s-2, Allied Signal Inc., Morristown, NJ) was adopted. Dry and oil-cooled, amorphous-core transformer prototypes were built. The joint research and development project was initiated with Transformateurs Ferranti-Packard Ltée, a company of Rolls-Royce Industries Canada Inc., to build and test a few units of high performance transformers on the Hydro-Québec power system.