准金属组元对压力下二元非晶合金的结构和物性影响

Pressure can change the atomic structures or even induce structural phase transitions in the amorphous alloys. Therefore, it is an efficient approach to manipulate their properties. However, due to the limitation of the experiment techniques, it is very difficult to accurately describe the local structure of the amorphous alloys. Thus, the mechanisms of the structural transformations in the amorphous alloys still remain unclear, and the perculiar behaviors of mechanical and electrical properties of the amorphous alloys under pressure cannot be explained at the atomic level. Recently, the applicant has studied the structures of Ce-Al and Ca-Al amorphous alloys with the first-principles method, the results show that the atomic size and the bonding mechanism are the key factors for the structural transformations. Compared to the metal-metal amorphous alloys, the metal-metalloid amorphous alloys should have a different bonding mechanism. However, the pressure induced structural transformations in the latter were much less investigated. Therefore, in the present project, the Au-Si and Au-Ge amorphous alloys will be used as models in order to investigate the structural transformations in metal-metalloid binary amorphous alloys, and the influences caused by the atomic size and bonding mechanisms of the metalloid elements on the structures and properties. It can be expected that the execution of this project will concur the limitation of the classic molecular dynamics method that its atomic potentials are not transferable at different pressures. It will let us not only systematically understand the mechanisms of the structural transformations in the amorphous alloys, but also could provide a new perspective to manipulate and improve the properties of the amorphous alloys such as mechanical and electrical properties.

非晶合金的结构和物性研究是材料科学领域的一大重点。压力能改变原子排列甚至诱导结构相变，因此是调制材料性能的一种有效手段。然而由于实验很难表征非晶合金的无序结构，人们对其压力下的结构变化规律仍不清楚，也无法从原子尺度解释压力下其力学和电学等性能的变化。最近申请人在Ce-Al和Ca-Al非晶合金的第一性原理计算研究中，发现压力下原子尺寸和成键机制的变化是体系发生多形态相变的重要原因。相比于全金属非晶合金，金属-准金属非晶合金其成键机制必然有所不同，但后者在压力下的研究甚少。鉴于此，本项目拟以Au-Si和Au-Ge等非晶合金为研究对象，通过第一性原理分子动力学方法和实验验证，研究压力下准金属组元对非晶合金结构和物性的影响。可以预见，本项目的实施将克服实验方法在表征无序结构上的局限性，从原子尺度深入理解非晶合金在压力下的微结构变化规律，为非晶合金材料力学和电学等性能的调制和优化提供新思路。

压力能改变非晶合金的原子结构甚至诱导结构相变，因此是调制其性能的一种有效手段。然而由于实验很难表征非晶合金的无序结构，人们对其压力下的结构相变机理至今仍无定论，也无法从原子尺度解释压力下其力学和电学等性能的变化。在之前Ce-Al和Ca-Al非晶合金的第一性原理计算研究中，我们发现压力下原子尺寸和成键机制的变化是体系发生多形态相变的重要原因。相比于全金属非晶合金，金属-准金属非晶合金的成键机制必然有所不同，但后者在压力下的研究甚少。鉴于此，本项目以Au-Si和Au-Ge等非晶合金为研究对象，通过第一性原理分子动力学方法研究了压力下准金属组元对二元非晶合金结构和物性的影响。研究发现，原子在常压下的性质在压力下可以发生显著的变化，从而影响非晶合金的结构和性质。本项目的实施为我们进一步加深了压力下成键机制对非晶合金结构和性质的影响，也为非晶合金材料力学和电学等性能的调制和优化提供新思路。