scholarly journals Grain Growth of AZ31 Magnesium Alloy Based on Three-Dimensional Cellular Automata

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yanfeng Li ◽  
Cuirong Liu ◽  
Zhibing Chu ◽  
Wei Li ◽  
Zhisheng Wu ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Cellular Automata ◽  
Grain Growth ◽  
Minimum Energy ◽  
Three Dimensional ◽  
Az31 Magnesium Alloy ◽  
Two Dimensional ◽  
Heat Preservation ◽  
Grain Diameter

Based on the thermodynamic conversion mechanism and energy transition principle, a three-dimensional cellular automata model of grain growth is established from the aspects of grain orientation, grain size distribution, grain growth kinetics, and grain topology. Also, the effect of temperature on the three-dimensional grain growth process of AZ31 magnesium alloy is analyzed. The results show that the normal growth of three-dimensional grains satisfies the Aboav-weaire equation, the average number of grain planes is between 12 and 14 at 420°C and 2000 CAS, and the maximum number of grain planes is more than 40. Grains of different sizes are distributed normally at different times, most of which are grains with the ratio of grain diameter to average grain diameter R/Rm ≈ 1.0, which meets the minimum energy criterion of grain evolution. The grain of AZ31 magnesium alloy increases in size with the increase of temperature, and the number of grains decreases with the increase in time. The angle between the two-dimensional slices of three-dimensional grains is approximately 120°, which is consistent with that of the traditional two-dimensional cellular automata. The relative error of grain size before and after heat preservation is in the range of 0.1–0.6 μm, which indicates that the 3D cellular automata can accurately simulate the heat preservation process of AZ31 magnesium alloy.

scholarly journals Microstructure Evolution and Grain Growth Model of AZ31 Magnesium Alloy under Condition of Isothermal

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Zhongtang Wang ◽  
Lingyi Wang ◽  
Lizhi Liu
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Growth ◽  
Growth Model ◽  
Microstructure Evolution ◽  
Heating Temperature ◽  
Holding Time ◽  
Az31 Magnesium Alloy ◽  
Temperature Range ◽  
Grain Growth Model

Microstructure evolution of AZ31 magnesium alloy in annealing process had been investigated by experiment study at heating temperature range of 150°C–450°C and holding time range of 15 min–60 min. The effects of heating temperature and holding time on grain growth had been analyzed. The results presented that the grain size tends to grow up with the increase of holding time at a certain temperature. At a certain holding time, the grain size increased firstly and then decreased at the heating temperature range of 150–250°C. And when heating temperature is higher than 250°C, the grain grows up gradually with the increase of heating temperature. The grain growth model of AZ31 Mg alloy has been established by regression based on the experimental data at temperature of 250–450°C, and the relative error between model calculation results and experimental results is less than 19.07%. Activation energy of grain growth of AZ31 magnesium alloy had been determined.

Microstructure Stability of a Fine-Grained AZ31 Magnesium Alloy Processed by Constrained Groove Pressing During Isothermal Annealing

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Kai Soon Fong ◽  
Ming Jen Tan ◽  
Fern Lan Ng ◽  
Atsushi Danno ◽  
Beng Wah Chua
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Growth ◽  
Isothermal Annealing ◽  
Az31 Magnesium Alloy ◽  
Growth Equation ◽  
Alloy Plate ◽  
Microstructure Stability ◽  
Average Grain Size

In this study, an AZ31 magnesium alloy plate was processed by constrained groove pressing (CGP) under three deformation cycles at temperatures from 503 to 448 K. The process resulted in a homogeneous fine grain microstructure with an average grain size of 1.8 μm. The as-processed microstructure contained a high fraction of low-angle grain boundaries (LAGB) of subgrains and dislocation boundaries that remained in the structure due to incomplete dynamic recovery and recrystallization. The material's yield strength was found to have increased from 175 to 242 MPa and with a significant weakening of its initial basal texture. The microstructure stability of the CGP-processed material was further investigated by isothermal annealing at temperature from 473 to 623 K and for different time. Abnormal grain growth was observed at 623 K, and this was associated with an increased in nonbasal grains at the expense of basal grains. The effect of annealing temperature and time on the grain growth kinetics was interpreted by using the grain growth equation,  Dn+D0n=kt, and Arrhenius equation, k=k0 exp (−(Q/RT)). The activation energy (Q) was estimated to be 27.8 kJ/mol which was significantly lower than the activation energy for lattice self-diffusion (QL = 135 kJ/mol) and grain boundary diffusion (Qgb = 92 kJ/mol) in pure magnesium. The result shows that grain growth is rapid but average grain size still remained smaller than the as-received material, especially at the shorter annealing time.

ACCUMULATIVE ROLL BONDING OF AZ31 MAGNESIUM ALLOY

2008 ◽  
Vol 22 (18n19) ◽  
pp. 2833-2939 ◽  
Author(s):  
S. M. FATEMI-VARZANEH ◽  
A. ZAREI-HANZAKI ◽  
M. HAGHSHENAS
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Accumulative Roll Bonding ◽  
Az31 Alloy ◽  
Thickness Reduction ◽  
Az31 Magnesium Alloy ◽  
Total Strain ◽  
Roll Bonding ◽  
Fine Grain

This work conducted to investigate the effects of accumulative roll bonding (ARB) method on achieving the ultra-fine grain microstructure in AZ31 alloy. Accordingly, a number of ARB routes at 400°C, applying thickness reductions per pass of 35%, 55%, and 85% were performed. The results indicate that both the final grain size and the degree of bonding have been dictated by the thickness reduction per pass. The larger pass reductions promote a higher degree of bonding. Increasing the total strain stimulates the formation of a more homogeneous ultra fine grain microstructure.

scholarly journals Recrystallization Microstructure Prediction of a Hot-Rolled AZ31 Magnesium Alloy Sheet by Using the Cellular Automata Method

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Ming Chen ◽  
Xiaodong Hu ◽  
Hongyang Zhao ◽  
Dongying Ju
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
Cellular Automata ◽  
Process Analysis ◽  
Rolling Process ◽  
Alloy Sheet ◽  
Az31 Magnesium Alloy ◽  
Rolled Sheet ◽  
Element Analysis ◽  
Hot Rolled

A large reduction rolling process was used to obtain complete dynamic recrystallization (DRX) microstructures with fine recrystallization grains. Based on the hyperbolic sinusoidal equation that included an Arrhenius term, a constitutive model of flow stress was established for the unidirectional solidification sheet of AZ31 magnesium alloy. Furthermore, discretized by the cellular automata (CA) method, a real-time nucleation equation coupled flow stress was developed for the numerical simulation of the microstructural evolution during DRX. The stress and strain results of finite element analysis were inducted to CA simulation to bridge the macroscopic rolling process analysis with the microscopic DRX activities. Considering that the nucleation of recrystallization may occur at the grain and R-grain boundary, the DRX processes under different deformation conditions were simulated. The evolution of microstructure, percentages of DRX, and sizes of recrystallization grains were discussed in detail. Results of DRX simulation were compared with those from electron backscatter diffraction analysis, and the simulated microstructure was in good agreement with the actual pattern obtained using experiment analysis. The simulation technique provides a flexible way for predicting the morphological variations of DRX microstructure accompanied with plastic deformation on a hot-rolled sheet.

Temporal Evolution of Grain Size Distributions in Two-Dimensional Pinned Cells

2004 ◽  
Vol 467-470 ◽  
pp. 1003-1008
Author(s):  
C.H. Wörner ◽  
A. Olguín
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Experimental Approach ◽  
Temporal Evolution ◽  
Size Distributions ◽  
Two Dimensional ◽  
Pinning Centers ◽  
Grain Size Distributions ◽  
Polycrystalline Aggregates

The distribution of sizes for grain growth in presence of pinning centers (Zener pinned growth) is communicated at different times. The experimental approach uses the well-known similitude between growth in polycrystalline aggregates and cellular soap froths. Two-dimensional results are communicated with grain growth limited by a set of randomly distributed rounded pins.

Zum Kornwachstum beim reinen und dotierten polykristallinen Selen / Grain Growth of Pure and Doped Poly crystalline Selenium

1971 ◽  
Vol 26 (7) ◽  
pp. 1198-1201
Author(s):  
C. Weyrich
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Grain Growth ◽  
Annealing Time ◽  
High Purity ◽  
The Mean ◽  
Grain Surface ◽  
Polycrystalline Form ◽  
Grain Diameter

Abstract Grain Growth of Pure and Doped Poly crystalline Selenium Samples of vitreous high-purity selenium as well as vitreous chlorine-and thallium-doped selenium have been brought into the polycrystalline form by annealing. The dependence of grain size on annealing time tu was measured. In high-purity selenium and in chlorine-doped selenium the mean grain diameter increases essentially ~ tu1/2 , in thallium-doped selenium ~ tu1/2 , as is expected from the laws of grain growth. The proportionality between electrical conductivity and specific grain surface reported by other authors could not be verified.

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