A numerical model has been developed to describe the microstructural evolution of Al In immiscible alloys through the miscibility gap. The model considers the common action of nucleation, diffusible growth, Brownian c...A numerical model has been developed to describe the microstructural evolution of Al In immiscible alloys through the miscibility gap. The model considers the common action of nucleation, diffusible growth, Brownian collision and motion collision between the second phase droplets. The simulation results are dynamically visualized and show that the volume fraction, distribution and size of the second phase droplets satisfactorily agree with the experimental results. So the model can be used to predict the microstructural evolution of Al In immiscible alloys during the cooling process.展开更多
A numerical model is presented describing the microstructure evolution of an immiscible alloy under the continuous casting conditions. Calculations are carried out to investigate the microstructure evolution in a vert...A numerical model is presented describing the microstructure evolution of an immiscible alloy under the continuous casting conditions. Calculations are carried out to investigate the microstructure evolution in a vertical strip cast sample of Al+5wt pct Pb alloy. The numerical results show that there exists a peak value for the supersaturation in front of the solid祃iquid interface, and the minority phase droplets are nucleated in a region around this peak. Under strip casting conditions the Marangoni migration dominates the motion of droplets. This leads to an accumulation of the minority phase droplets in front of the solid祃iquid interface.展开更多
Vaporizing foil actuator spot welding method is used in this paper to join magnesium alloy AZ31 and uncoated high-strength steel DP590,which are typically considered as un-weldable due to their high physical property ...Vaporizing foil actuator spot welding method is used in this paper to join magnesium alloy AZ31 and uncoated high-strength steel DP590,which are typically considered as un-weldable due to their high physical property disparities,low mutual solubility,and the lack of any intermetallic phases.Characterization results from scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(HRTEM)of the weld interface indicate that the impact creates an Mg nanocrystalline interlayer with abundant Fe particles.The interlayer exhibits intact bonding with both DP590 and AZ31 substrates.To investigate the fundamental bond formation mechanisms at the interface,a finite element(FE)-based process simulation is first performed to calculate the local temperature and deformation at the interface under the given macroscopic experimental condition.Taking the FE results at the interface as inputs,molecular dynamics(MD)simulations are conducted to study the interlayer formation at the Mg/Fe interface during the impact and cooling.The results found a high velocity shearing-induced mechanical mixing mechanism that mixes Mg/Fe atoms at the interface and creates the interlayer,leading to the metallurgical bond between Mg/steel alloys.展开更多
文摘A numerical model has been developed to describe the microstructural evolution of Al In immiscible alloys through the miscibility gap. The model considers the common action of nucleation, diffusible growth, Brownian collision and motion collision between the second phase droplets. The simulation results are dynamically visualized and show that the volume fraction, distribution and size of the second phase droplets satisfactorily agree with the experimental results. So the model can be used to predict the microstructural evolution of Al In immiscible alloys during the cooling process.
文摘A numerical model is presented describing the microstructure evolution of an immiscible alloy under the continuous casting conditions. Calculations are carried out to investigate the microstructure evolution in a vertical strip cast sample of Al+5wt pct Pb alloy. The numerical results show that there exists a peak value for the supersaturation in front of the solid祃iquid interface, and the minority phase droplets are nucleated in a region around this peak. Under strip casting conditions the Marangoni migration dominates the motion of droplets. This leads to an accumulation of the minority phase droplets in front of the solid祃iquid interface.
基金sponsored by the US Department of Energy,Office of Vehicle Technology,under a prime contract with Oak Ridge National Laboratory(ORNL)。
文摘Vaporizing foil actuator spot welding method is used in this paper to join magnesium alloy AZ31 and uncoated high-strength steel DP590,which are typically considered as un-weldable due to their high physical property disparities,low mutual solubility,and the lack of any intermetallic phases.Characterization results from scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(HRTEM)of the weld interface indicate that the impact creates an Mg nanocrystalline interlayer with abundant Fe particles.The interlayer exhibits intact bonding with both DP590 and AZ31 substrates.To investigate the fundamental bond formation mechanisms at the interface,a finite element(FE)-based process simulation is first performed to calculate the local temperature and deformation at the interface under the given macroscopic experimental condition.Taking the FE results at the interface as inputs,molecular dynamics(MD)simulations are conducted to study the interlayer formation at the Mg/Fe interface during the impact and cooling.The results found a high velocity shearing-induced mechanical mixing mechanism that mixes Mg/Fe atoms at the interface and creates the interlayer,leading to the metallurgical bond between Mg/steel alloys.
