The Solidification Of Al-Cu Alloy Melt Induced By Substrate

Aluminum-copper alloy is widely used in automobile manufacturing,industrial production,aerospace and other fields because of low density and high hardness.Solidification is a physical phenomenon that must be experienced in the process of casting process and material preparation of Al-Cu alloy.Nucleation occurs during solidification,which can be divided into homogeneous nucleation and heterogeneous nucleation.However,the industrial applications in real life usually use heterogeneous nucleation,so it is of great significance to study the influence of substrates on the solidification process of Al-Cu melt,and it is also the first problem to be solved for improving the casting properties of Al-Cu alloy.In this paper,we use the molecular dynamics to study the solidification of Al-Cu melt in a single substrate and confined space was studied by,and also found he abnormal solidification behavior of Al-Cu melt on a wedge-shaped substrate,at the same time we studied the variation of dislocation lines in alloys.The intrinsic relationship between the substrate and the structure of Al-Cu melt was revealed.The results are of great significance for improving the casting properties of Al-Cu alloys by controlling the substrates to change the structure of Al-Cu alloys.This paper is divided into four parts:Three types of copper substrates with different shapes were selected,namely,single substrate,confined space formed by two parallel substrates and wedge-shaped substrates with different angles.Molecular dynamics method was used to simulate the solidification process of Al-Cu alloys with different concentrations on these substrates.(1)We studied the solidifaction of Al-Cu melt on a single substrate.The results show that the Al-Cu melt next to the substrate will first form an ordered atomic layer,and then grows as a new substrate to continue to attract new atoms.The whole melt will solidify in this layer-by-layer growth mode.This growth phenomenon will change with the composition of the melt,and the substrate will also transmit its crystal structure information to the melt.(2)We stdudiedThe solidification behavior of Al-Cu melt in confined space.In the confined space,the melt near the substrate will stil]solidify layer by layer,but the part of melt away from the substrate will form a bridge in the middle of the melt,and as the copper content increases,the "bridge" increases first,then decreases,and finally disappears..(3)We sudied the solidification of Al-Cu melt on wedge-shaped substrates.It is found that the pure aluminum melt solidifies on the wedge-shaped substrate in a layer-by-layer growth mode,and the same angle with the substrate will be formed inside the melt.However,when the melt becomes Al-Cu melt,the layer-by-layer growth will disappear.Instead,the Al-Cu melt away from the substrate will begin to solidify at first.After solidification,the solid near the substrate will remain disordered.(4)We studied the dislocation distribution of the alloy at different cooling rates and concentrations.It is found that there is a mathematical relationship between dislocation line length and copper content of Al-Cu alloy solidified on copper substrate,but dislocation line length is not very sensitive to cooling rate.