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运用分子动力学模拟方法,采用镶嵌原子势,研究了金属Cu和Ni3Al在发生玻璃转变过程中的势能曲面.我们计算了两种金属的内在结构(Inherent Structure简称IS),发现它们的内在势能在整个降温区间分为三个阶段:高温时,内在势能在一个较高的能量值附近波动;当系统的温度降低到熔点温度(Tm)时,内在势能大幅度减小;当体系温度降到玻璃转变温度(Tg)时,内在势能变得平稳.本文将Cu,Ni3Al和Lennard-Jones Binary Mixtures(BMLJ)液体的内在势能进行了比较,发现金属势能曲面与BMLJ液体的势能曲面存在明显的差异,与BMLJ液体相比,Cu和Ni3Al在高低温的内在势能差值很小,尤其是Cu的内在能量几乎不随温度变化,其差值的大小反映了液体的动力学性质的强弱.文章统计了Cu和Ni3Al在不同温度下内在能量的概率分布,并计算了两种金属内在结构的海森矩阵特征值的概率分布,发现Ni3Al的势能曲面比Cu的势能曲面更粗糙,更易形成非晶.我们提出了一个由势能曲面计算流变激活能的新方法,并计算了Cu和Ni3Al的流变激活能,发现它们的激活能都随着温度的降低而升高,但是Ni3Al的激活能随温度降低升高得更快,在玻璃转变点附近,Ni3Al的激活能比Cu的激活能要高,这与Ni3Al比Cu有更好的玻璃形成能力有着密切的联系.金属的势能曲面的特征决定了金属的玻璃形成能力.
By using molecular dynamics simulations and inlaying atomic potential, the potential energy surfaces of Cu and Ni3Al during glass transition have been studied. We calculated the intrinsic structures of two metals (IS) and found that their intrinsic potential The whole cooling interval is divided into three phases: the intrinsic potential energy fluctuates around a high energy value at high temperature, the intrinsic potential energy decreases greatly when the system temperature decreases to the melting temperature (Tm) Intrinsic potential energy becomes stable at the transition temperature (Tg) .In this paper, we compare the intrinsic potential of Cu, Ni3Al and Lennard-Jones Binary Mixtures (BMLJ) liquids, and find that there is a significant difference between the potential energy surface of the metal potential surface and the BMLJ liquid, Compared with BMLJ liquid, Cu and Ni3Al have a small intrinsic potential difference at high temperature and low temperature, especially the intrinsic energy of Cu hardly changes with temperature, and the difference reflects the strength of the liquid’s dynamic properties. Cu and Ni3Al at different temperatures, and calculate the probability distribution of internal energy of two kinds of metal intrinsic structure. It is found that the potential energy surface of Ni3Al is larger than that of Cu We have proposed a new method to calculate rheological activation energy from the potential energy surface and calculated the rheological activation energy of Cu and Ni3Al and found that their activation energy decreases with the decrease of temperature But the activation energy of Ni3Al increases faster with the temperature decrease. The activation energy of Ni3Al is higher than the activation energy of Cu near the glass transition point, which is close to the better glass formation ability of Ni3Al than Cu The characteristic of the potential energy surface of a metal determines the glass’s ability to form a metal.