The structure of metallic glasses has been a long-standing mystery. Owing to the disordered nature of atomic structures in metallic glasses, it is a great challenge to find a simple structural description, such as per...The structure of metallic glasses has been a long-standing mystery. Owing to the disordered nature of atomic structures in metallic glasses, it is a great challenge to find a simple structural description, such as periodicity for crystals, for establishing the structure–property relationship in amorphous materials. In this paper, we briefly review the recent developments of the five-fold local symmetry in metallic liquids and glasses and the understanding of the structure–property relationship based on this parameter. Experimental evidence demonstrates that five-fold local symmetry is found to be general in metallic liquids and glasses. Comprehensive molecular dynamics simulations show that the temperature evolution of five-fold local symmetry reflects the structural evolution in glass transition in cooling process, and the structure–property relationship such as relaxation dynamics, dynamic crossover phenomena, glass transition, and mechanical deformation in metallic liquids and glasses can be well understood base on the simple and general structure parameter of five-fold local symmetry.展开更多
以125种含水二元共沸物为研究对象,基于定量结构-性质关系,对该类共沸物在常压下的共沸温度及组成进行了预测研究,分别建立了多个预测模型。首先,利用HyperChem 8.0软件绘制了纯组分的三维分子结构,并利用分子力学方法和量子力学半经验...以125种含水二元共沸物为研究对象,基于定量结构-性质关系,对该类共沸物在常压下的共沸温度及组成进行了预测研究,分别建立了多个预测模型。首先,利用HyperChem 8.0软件绘制了纯组分的三维分子结构,并利用分子力学方法和量子力学半经验方法对分子结构进行优化;然后,利用Materials Studio 8.0软件计算纯物质的分子描述符;其次,利用遗传算法分别筛选出与共沸温度及组成最为密切的特征描述符;再运用多元线性回归方法建立了6个共沸温度预测模型及5个共沸组成预测模型,并对模型的稳定性、拟合能力和预测能力进行对比分析;最后,对最适宜模型分别进行内部验证、外部验证、应用域分析、与文献中同类模型及UNIFAC基团贡献法进行对比。结果表明:最适宜共沸温度/组成预测模型分别是利用8/5个特征描述符所建立的模型;其复相关系数,调整复相关系数,均方根误差,平均绝对误差,留一法交叉验证系数和外部验证系数分别为0.9606/0.9970、0.9572/0.9969、2.9400/0.0161、1.8900/0.0104、0.9475/0.9957和0.9439/0.9976,且模型的稳定性、预测能力和泛化能力均优同类模型。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51271195 and 51271197) the National Basic Research Program of China(Grant No.2015CB856800)+1 种基金 the Fundamental Research Funds for the Central Universities,China the Research Funds of Renmin University of China(Grnat No.16XNLQ01)
文摘The structure of metallic glasses has been a long-standing mystery. Owing to the disordered nature of atomic structures in metallic glasses, it is a great challenge to find a simple structural description, such as periodicity for crystals, for establishing the structure–property relationship in amorphous materials. In this paper, we briefly review the recent developments of the five-fold local symmetry in metallic liquids and glasses and the understanding of the structure–property relationship based on this parameter. Experimental evidence demonstrates that five-fold local symmetry is found to be general in metallic liquids and glasses. Comprehensive molecular dynamics simulations show that the temperature evolution of five-fold local symmetry reflects the structural evolution in glass transition in cooling process, and the structure–property relationship such as relaxation dynamics, dynamic crossover phenomena, glass transition, and mechanical deformation in metallic liquids and glasses can be well understood base on the simple and general structure parameter of five-fold local symmetry.
文摘以125种含水二元共沸物为研究对象,基于定量结构-性质关系,对该类共沸物在常压下的共沸温度及组成进行了预测研究,分别建立了多个预测模型。首先,利用HyperChem 8.0软件绘制了纯组分的三维分子结构,并利用分子力学方法和量子力学半经验方法对分子结构进行优化;然后,利用Materials Studio 8.0软件计算纯物质的分子描述符;其次,利用遗传算法分别筛选出与共沸温度及组成最为密切的特征描述符;再运用多元线性回归方法建立了6个共沸温度预测模型及5个共沸组成预测模型,并对模型的稳定性、拟合能力和预测能力进行对比分析;最后,对最适宜模型分别进行内部验证、外部验证、应用域分析、与文献中同类模型及UNIFAC基团贡献法进行对比。结果表明:最适宜共沸温度/组成预测模型分别是利用8/5个特征描述符所建立的模型;其复相关系数,调整复相关系数,均方根误差,平均绝对误差,留一法交叉验证系数和外部验证系数分别为0.9606/0.9970、0.9572/0.9969、2.9400/0.0161、1.8900/0.0104、0.9475/0.9957和0.9439/0.9976,且模型的稳定性、预测能力和泛化能力均优同类模型。