Experimental Study and Numerical Simulation of Microstructure Evolution in Al-Si Eutectic Solidification Process

2018 ◽  
Vol 913 ◽  
pp. 212-219 ◽  
Author(s):  
Bing Wu ◽  
Ao Lei Jiang ◽  
Hao Lu ◽  
Hong Liang Zheng ◽  
Xue Lei Tian
Keyword(s):  
Numerical Simulation ◽  
Microstructure Evolution ◽  
Solidification Process ◽  
Eutectic Growth ◽  
Eutectic Structure ◽  
Solute Concentration ◽  
Optical Microscope ◽  
Eutectic Solidification ◽  
Eutectic Si ◽  
Ca Model

A mathematical physical model of microstructure evolution in Al-Si eutectic solidification process based on cellular automaton (CA) model was developed. Before the establishment of the model, the relevant near-eutectic experiments were carried out to analyze the effect of cooling rates measured by temperature curves on the eutectic structure which was observed through optical microscope (OM) and scanning electron microscope (SEM). Then a multiphase nucleation-growth CA model was applied to simulate the Al-Si irregular eutectic structure. The model adopted an alternative nucleation mechanism to investigate the influence of the critical nucleation value associated with solute concentration during solidification process. The growth kinetics took into account the solute and thermal field. According to the crystal structure of nonfaceted eutectic Al and faceted eutectic Si, different capturing rules were employed to calculate the growth of eutectic. In addition, the model was also used to research the irregular eutectic growth under different undercooling conditions. The results revealed that smaller critical nucleation value (absolute value) or higher eutectic undercooling tended to get a more refined eutectic microstructure. By compared with experimental results, it is indicated that the microstructure evolution of Al-Si eutectic growth can be reproduced quantitatively by numerical simulation with this model.

PHASE-FIELD MODELING OF ELASTIC EFFECTS IN EUTECTIC GROWTH WITH MISFIT STRESSES

2012 ◽  
Vol 04 (01) ◽  
pp. 1250024
Author(s):  
ZOHREH EBRAHIMI ◽  
JOAO REZENDEH
Keyword(s):  
Phase Field ◽  
Elastic Energy ◽  
Field Model ◽  
Phase Field Model ◽  
Solidification Process ◽  
Eutectic Growth ◽  
Point Of View ◽  
Eutectic Solidification ◽  
Elastic Model ◽  
Sharp Interface Model

Elastic interactions, arising from a difference of lattice spacing between two coherent phases in eutectic alloys with misfit stresses, can have an influence on microstructural pattern formation of eutectic colonies during solidification process. From a thermodynamic point of view the elastic energy contributes to the free energy of the phases and modifies their mutual stability. Therefore, the elastic stresses will have an effect on stability of lamellae, lamellae spacing and growth modes. In this paper, a phase-field model is employed to investigate the influence of elastic misfits in eutectic growth. The model reduces to the traditional sharp-interface model in a thin-interface limit, where the microscopic interface width is small but finite. An elastic model is designed, based on linear microelasticity theory, to incorporate the elastic energy in the phase-field model. Theoretical and numerical approaches, required to model elastic effects, are formulated and the stress distributions in eutectic solidification structures are evaluated. The two-dimensional simulations are performed for directed eutectic growth and the simulation results for different values of the misfit stresses are illustrated.

scholarly journals Cellular Automaton Modeling of Phase Transformation of U-Nb Alloys during Solidification and Consequent Cooling Process

2019 ◽  
Vol 38 (2019) ◽  
pp. 567-575 ◽  
Author(s):  
Qingfu Tang ◽  
Dong Chen ◽  
Bin Su ◽  
Xiaopeng Zhang ◽  
Hongzhang Deng ◽  
...  
Keyword(s):  
Cellular Automaton ◽  
Microstructure Evolution ◽  
Optical Microscope ◽  
Phase Precipitation ◽  
Cooling Process ◽  
Dendrite Morphology ◽  
Ca Model ◽  
Measuring Experiment ◽  
Kinetics Of ◽  
Cast Microstructure

AbstractThe microstructure evolution of U-Nb alloys during solidification and consequent cooling process was simulated using a cellular automaton (CA) model. By using this model, ϒ phase precipitation and monotectoid decomposition were simulated, and dendrite morphology of ϒ phase, Nb microsegregation and kinetics of monotectoid decomposition were obtained. To validate the model, an ingot of U-5.5Nb (wt.%) was produced and temperature measuring experiment was carried out. As-cast microstructure at different position taken from the ingot was investigated by using optical microscope and SEM. The effect of cooling rate on ϒ phase precipitation and monotectoid decomposition of U-Nb alloys was also studied. The simulated results were compared with the experimental results and the capability of the model for quantitatively predicting the microstructure evolution of U-Nb alloys during solidification and consequent cooling process was assessed.

A Simplified CA Method for Simulating the Microstructure of Magnesium Alloy Components

2007 ◽  
Vol 561-565 ◽  
pp. 1797-1800 ◽  
Author(s):  
Liang Huo ◽  
Zhi Qiang Han ◽  
Zhi Yong Liu ◽  
Bai Cheng Liu
Keyword(s):  
Magnesium Alloy ◽  
Solidification Process ◽  
Eutectic Structure ◽  
Competitive Growth ◽  
Az91d Magnesium Alloy ◽  
Ca Model ◽  
Simulation Results ◽  
Evolution Of Microstructure ◽  
Crystallographic Orientations ◽  
Good Agreement

In this paper, a simplified cellular automaton (CA) model was proposed for modeling the evolution of microstructure in solidification process of AZ91D magnesium alloy. Since the calculation time was significantly reduced, it might be used to predict the microstructure field of a real Mg component after solidification. The stochastic nucleation, competitive growth processes of many grains with various crystallographic orientations and the formation of eutectic structure were also taken into account. Furthermore, step castings were poured with sand and permanent molds and metallographic experiments were carried out for validating the developed models. It was shown that the simulation results are in good agreement with those obtained in the experiments.

Microstructure Simulation of Die Casting AZ91D Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 109-112
Author(s):  
Z.Y. Liu ◽  
Qing Yan Xu ◽  
Bai Cheng Liu
Keyword(s):  
Microstructure Evolution ◽  
Die Casting ◽  
Three Dimensional ◽  
Solidification Process ◽  
Solute Concentration ◽  
Primary Phase ◽  
Az91d Alloy ◽  
Cylinder Head Cover ◽  
Physical And Mathematical Models ◽  
Head Cover

Physical and mathematical models of microstructure evolution during the solidification process of die casting AZ91D alloy were investigated in this paper. Coupled with solute concentration, a modified three-dimensional cellular automaton (CA) model was proposed. Considering the solute enrichment and the formation of eutectic microstructure, these models can reproduce the whole microstructure evolution process of Mg alloy, from the formation of primary phase to the eutectic transformation. The microstructure of the AZ91D alloy cylinder head cover die casting was simulated with the proposed models. The simulated results are in agreement with the experimental.

scholarly journals Phase Formation and Microstructure Evolution of Al-5Si-0.8Mg Alloys with Different Mn Concentrations

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 308
Author(s):  
Ni Tian ◽  
Guangdong Wang ◽  
Yiran Zhou ◽  
Chuncheng Liu ◽  
Kun Liu ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Phase Formation ◽  
Microstructure Evolution ◽  
Thermodynamic Calculation ◽  
Solidification Process ◽  
Eutectic Structure ◽  
Experimental Results ◽  
Alloying Element ◽  
Mn Content ◽  
Mn Concentrations

Mg-containing high-Si aluminum alloys are heat-treatable alloys that are widely used in industry. Substantial attention has been paid to increasing the performance of such alloys by adding a small amount of Mn, which is an effective and common alloying element in aluminum alloys. In the present work, the solidification process of Mn-free Al-5Si-0.8Mg alloy and Al-5Si-0.8Mg-(0.45–1.97)Mn alloys are analyzed by the experimental results combined with thermodynamic calculation. The results showed that α-Al, Si, Mg2Si and π (Al8Mg3FeSi6) are predominant phases in the Mn-free Al-5Si-0.8Mg alloy while the π (Al8Mg3FeSi6) phase are transformed to α-Al(FeMn)Si phase with the addition of 0.45% Mn. With increasing Mn addition to 0.72%, the L→α-Al was replaced by L→α-Al(FeMn)Si and a primary α-Al(FeMn)Si phase appeared. Further increasing the Mn to 1.97%, the solidification reactions remained unchanged. However, the size and number of the primary α-Al(FeMn)Si phase gradually increased, while the divorced eutectic phenomenon of quaternary eutectic structure gradually weakened. Meanwhile, the Mg2Si phase in the quaternary eutectic structure gradually transformed from blocky to fine eutectic lamellar, and the quaternary eutectic structure was significantly refined. Primary blocky α-Al(FeMn)Si began to form when the Mn content was higher than 0.75%.

scholarly journals Numerical simulation of microstructure evolution and microsegregation of U-Nb alloy during solidification process

China Foundry ◽  
2017 ◽  
Vol 14 (5) ◽  
pp. 412-415 ◽  
Author(s):  
Bin Su ◽  
Zhi-qiang Han ◽  
Hong-zhang Deng ◽  
Rong Ma ◽  
Dong Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Microstructure Evolution ◽  
Solidification Process

Numerical Simulation of Filling and Solidification in Sand Casting by Procast

2013 ◽  
Vol 791-793 ◽  
pp. 550-553 ◽  
Author(s):  
Dong Dong Han ◽  
Cheng Jun Wang ◽  
Juan Chang ◽  
Lei Chen ◽  
Huai Bei Xie
Keyword(s):  
Numerical Simulation ◽  
Heat Dissipation ◽  
Solidification Process ◽  
Simulation Software ◽  
Sand Casting ◽  
Production Costs ◽  
Raw Material ◽  
Casting Defects ◽  
Three Dimension ◽  
Filling And Solidification

At present, pulley produced in China has been able to meet the demand of domestic and international markets. But there are many problem of the pulley industry in our country, such as too many production enterprises and the low level of export products. And as components of drive system are light weight and raw material price of pulley casting are rising, manufacturing requirements of the pulley are also more and more high. Aiming at the casting defects of pulley that enterprise current product, pulley casting blank model of common material HT250 be made by three-dimension software, numerical simulation of filling and solidification process for pulley sand casting by the casting simulation software Procast, the size and location of the various casting defects were forecasted and analyzed, reflecting the pulley filling and solidification process of the actual situation, due to the thicker pulley rim and less heat dissipation, position of shrinkage is close to the middle of rim [, a method of eliminating defects is proposed to realize sequential solidification, and thus to minimize porosity shrinkage and improve casting performance and reduce casting time and reduce production costs.

Electron Back Scattering Diffraction Analysis of A357 Alloy Modified by Sr

2010 ◽  
Vol 160-162 ◽  
pp. 831-835
Author(s):  
Zhong Wei Chen ◽  
Hai Fang Zhang ◽  
Jiang Chao Zhao
Keyword(s):  
Cast Alloy ◽  
Primary Aluminum ◽  
Mapping Technique ◽  
Eutectic Solidification ◽  
Preparation Technique ◽  
Ion Milling ◽  
A357 Alloy ◽  
Back Scattering ◽  
Eutectic Si ◽  
Eutectic Morphology

Microstructure of A357 alloy modified by Sr has been investigated by the Electron Back Scattering Diffraction (EBSD) mapping technique using a Field Emission Gun Scanning Electron Microscopy (FEG-SEM). An appropriate sample preparation technique by ion milling was applied to obtain a sufficiently smooth surface for EBSD mapping. Results show that the eutectic morphology in microstructure of A357 alloy modified by Sr was changed to fine fibrous, and the grain size was refined. By comparing the orientation of the aluminum in the eutectic to that of the primary aluminum dendrites, the nucleation and growth mechanism of the eutectic solidification in A357 cast alloy was determined. The eutectic Si phase of the modified sample nucleates on the heterogeneous nuclei located in the region between primary α-Al dendrites and grows up, while the eutectic Si phase of the sample without modification nucleates on the primary α-Al dendrites and grows up.

Effect of Warm Deformation on Ferrite Microstructure Evolution in a Ti-Microalloyed Steel

2007 ◽  
Vol 558-559 ◽  
pp. 497-504
Author(s):  
Beitallah Eghbali
Keyword(s):  
Microstructure Evolution ◽  
Microalloyed Steel ◽  
Early Stage ◽  
Microstructural Analysis ◽  
Optical Microscope ◽  
Low Carbon ◽  
High Angle ◽  
Warm Deformation ◽  
Continuous Dynamic Recrystallization ◽  
Continuous Dynamic

Warm deformation is one of the promising hot rolling strategies for producing thin hot rolled steel strips. A better understanding of the microstructure evolution during warm deformation is important for a successful introduction of such processing into the industrial production. In the present research, the effect of deformation strain on the ferrite microstructure development in a low carbon Ti-microalloyed steel was investigated through warm torsion testing. Microstructural analysis with optical microscope and electron back-scattering diffraction was carried out on the warm deformed ferrite microstructures. The results show that at the early stage of deformation an unstable subboundaries network forms and low angle boundaries are introduced in the original grains. Then, with further straining, low angle boundaries transform into high angle boundaries and stable fine equiaxed ferrite grains form. It was considered that dynamic softening and dynamically formation of new fine ferrite grains, with high angle boundaries, were caused by continuous dynamic recrystallization of ferrite.

Sign in / Sign up

Export Citation Format

Share Document