Rapid Solidification Simulation And Microstructure Analysis Of Electronic Material AuSi Alloy

The popularization of the Internet facilitates the circulation of information,and also makes ever As a typical metal semiconductor material,AuSi has received extensive attention both in theory and application.In this paper,molecular dynamics(MD)method and novel AuSi alloy potential function are used to simulate the rapid solidification process of liquid AuSi alloys under different conditions.The Energy curve,Pair distribution function,Bond-type index,Cluster analysis and Structure visualization methods are used to in-depth explore the solidification law and microscopic evolution mechanism of the alloys.Firstly,A molecular dynamics(MD)simulation has been conducted to investigate the Si-like and topologically close-packed(TCP)structures in Au_xSi_(100-x)alloys during rapid solidification at the cooling rate of 10¹¹K/s.A new method named largest standard cluster analysis(LSCA)is performed to analyze and characterize the microstructural evolution during solidification.Results indicate that it is difficult to crystallize for each kind of Au-Si alloy,but eventually freeze into amorphous solids.The Si-like structures with low coordination number are significantly formed in the Si-rich alloys with Au content C_Au?30%,while TCP structures with higher packing density prefer to form in the Au-rich alloys with C_Au?80%.Moreover,the Si-like Medium-range order(MRO)structures are more likely to link with each other by 1100 bond-type,while the more denser TCP MROs are inclined to combine by 1551 bond-type.Secondly,The rapid solidification process of liquid Si-rich Au20Si80 alloy has been simulated at four cooling rate 10¹¹K/s?10¹²K/s?10¹³K/s and 10¹⁴K/s.It is focus on studying the effect on Si-like structure of cooling rate.The results show that the cooling rate will not only qualitatively determine whether the system is crystalline or amorphous,but also quantitatively cause the difference in microstructure.The higher the cooling rate,the more unconventional amorphous structures.However,The lower the cooling rate,the easier it is to form Si-like structures;The cooling rate has no effect on the elemental composition of the central atoms in the Si-like structures,and almost central atoms of the Si-like structures are Si atoms.At a low cooling rate 10¹¹K/s,the peripheral atomic elements of Si-A-like,Si-B-like,Si-C-like and Si-D-like with Si as the center are mainly composed of 4 Si and 1 Au atoms.The coordination number of Si-like-E with Si atom as the center is 4,and the neighbours in Si-centred structure is mainly 4 Si atoms.By comparing the average atomic energy of the five types in Si structures,the stabilities of five Si-like structures are Si-like-E,Si-like-B,Si-like-C,Si-like-A and Si-like-D from high to low.Finally,the simulation study of the rapid solidification process in the amorphous Au-rich Au₇₅Si₂₅alloy at a cooling rate of 10¹¹K/s,focusing on the study of its local structural characteristics and evolution laws.The results are as follows:Among the three partial g(r),the first peak of g _Au-Si(r)is the highest,indicating that the interaction between Au and Si is strong and the two are mixed well with no segregation,which is consistent with the results of previous simulation.The coordination number analysis further proved that Au and Si are mixed well,and the coordination numbers in the system are varied and unevenly distributed,which leads to the structures in alloy are disordered and complex.From the perspective of bond-type,the sum of the relative proportion in amorphous bond-type gradually takes the dominant position during the solidification process,indicating that the clusters composed of the amorphous bond type gradually expand the influence on the properties of the alloy,A parameter D_mixis proposed to describe the degree of mixing.By observing the D_mixevolution with temperature,it is found that the mixing degree of Au and Si atoms is higher and more stable at low temperature.