Influence of Al,Cu and Mn additions on diffusion behaviors in CoCrFeNi high-entropy alloys

The interdiffusion coefficients in Al_(0.2)CoCrFeNi,CoCrCu_(0.2)FeNi,and CoCrFeMn_(0.2)Ni high-entropy alloys were efficiently determined by combining diffusion couple experiments and high-throughput determination of interdiffusion coefficients(HitDIC)software at 1273−1373 K.The results show that the addition of Al,Cu,and Mn to CoCrFeNi high-entropy alloys promotes the diffusion of Co,Cr,and Fe atoms.The comparison of tracer diffusion coefficients indicates that there is no sluggish diffusion in tracer diffusion on the thermodynamic temperature scale for the present Al_(0.2)CoCrFeNi,CoCrCu_(0.2)FeNi,and CoCrFeMn_(0.2)Ni high-entropy alloys.The linear relationship between diffusion entropy and activation energy reveals that the diffusion process of atoms is unaffected by an increase in the number of components as long as the crystal structure remains unchanged.

超临界二氧化碳在非常规油气藏开发中的应用

由于超临界二氧化碳既具有气体的低粘度和高扩散系数又具有液体的高密度的性质,近年来已逐渐引起石油行业的广泛关注。国外已针对超临界二氧化碳在非常规油气藏开发中的应用进行了大量的研究,并将各项技术运用于钻井、压裂、混相驱油等现场施工中,取得了很好的效果。我国超临界二氧化碳在石油方面的运用处于起步阶段,还拥有巨大的潜力,超临界二氧化碳也必将成为未来石油行业的研究热点。

Effects of Perfectly Correlated and Anti-Correlated Noise in a Logistic Growth Model

The logistic growth model with correlated additive and multiplicative Gaussian white noise is used to anedyze tumor cell population. The effects of perfectly correlated and anti-correlated noise on the stationary properties of tumor cell population are studied. As in both cases the diffusion coefficient has zero point in real number field, some special features of the system are arisen. It is found that in cause tumor cell extinction. In the perfectly anti-correlated tumor cell population exhibit two extrema. both cases, the increase of the multiplicative noise intensity case, the stationary probability distribution as a function of

Influence of wave normal angle on gyroresonance between chorus waves and outer radiation belt electrons

In this paper, using a Gaussian distribution of wave normal angle X=tan0, and considering contributions of harmonic resonances n up to ＋5, we analyze the effect of normal angle on diffusion coefficients induced by gyroresonance between chorus waves and electrons with energies 0.1 and 1.0 MeV on the dayside and nightside at L=4.5. When pitch angle a~〉10~, for 0.1 and 1,0 MeV electrons on the dayside and nightside, diffusion coefficients of five orders （-2, -1, 0, 1, 2） decrease with in- creasing normal angle peak, leading to the total diffusion coefficients decreasing with increasing peak. When ae〈10~, for 1.0 MeV electrons on the dayside and 0.1 MeV electrons on the dayside and nightside, the positive order diffusion coefficients are generally smaller than the same negative order ones; in the meanwhile, diffusion coefficients of orders （-2, 1, 2） are very small, the dominant order n=-I diffusion coefficients change very little, hence the total diffusion coefficients almost remain un- changed. However, for 1.0 MeV electrons on the nightside, diffusion coefficients of orders （-2, 1, 2） which are larger than those of the order （-1） resonance increase with increasing peak, hence the total diffusion coefficients increase with increasing peak. The current results show that the wave normal angle plays an important role in the quantitative analysis of gyroresonance between chorus waves and electrons in the outer radiation belt.

The existence and non-existence of travelling front in high order auto-catalysis chemical reaction

This article studies propagating wave fronts in an isothermal chemical reaction A + nB →(n + 1)B involving two chemical species,a reactant A and an auto-catalyst B whose diffusion coefficients,DA and DB,are unequal due to different molecular weights and/or sizes.More accurate bounds v* and v* that depend on DB/DA,when the ratio is less than 1,are derived such that there is a unique travelling wave of every speed v v* and there does not exist any travelling wave of speed v < v*.The refined bounds for DB/DA < 1 case is compatible to what has been shown in earlier work for DB/DA > 1 when n 3.