scholarly journals Grain Refinement by Second Phase Particles under Applied Stress in ZK60 Mg Alloy with Y through Phase Field Simulation

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1903 ◽  
Author(s):  
Yuhao Song ◽  
Mingtao Wang ◽  
Yaping Zong ◽  
Ri He ◽  
Jianfeng Jin
Keyword(s):  
Grain Refinement ◽  
Applied Stress ◽  
Phase Field ◽  
Phase Particle ◽  
Alloy System ◽  
Second Phase ◽  
Recrystallization Process ◽  
Time Space ◽  
Second Phase Particles ◽  
Zk60 Alloy

Based on the principle of grain refinement caused by the second-phase particles, a phase field model was built to describe the recrystallization process in the ZK60 alloy system with Y added under applied stress between temperatures 573 and 673 K for 140 min duration. The simulation of grain growth with second phase particles and applied stress during annealing process on industrial scale on the condition of real time-space was achieved. Quantitative analysis was carried out and some useful laws were revealed in ZK60 alloy system. The second phase particles had a promoting effect on the grain refinement, however the effect weakened significantly when the content exceeded 1.5%. Our simulation results reveal the existence of a critical range of second phase particle size of 0.3–0.4 μm, within which a microstructure of fine grains can be obtained. Applied stress increased the grain coarsening rate significantly when the stress was more than 135 MPa. The critical size of the second phase particles was 0.4–0.75 μm when the applied stress was 135 MPa. Finally, a microstructure with a grain size of 11.8–13.8 μm on average could be obtained when the second phase particles had a content of 1.5% and a size of 0.4–0.75 μm with an applied stress less than 135 Mpa after 30 min annealing at 573 K.

scholarly journals Phase-Field Simulation of Grain Boundary Evolution In Microstructures Containing Second-Phase Particles with Heterogeneous Thermal Properties

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
T. F. Flint ◽  
Y. L. Sun ◽  
Q. Xiong ◽  
M. C. Smith ◽  
J. A. Francis
Keyword(s):  
Thermal Properties ◽  
Grain Boundaries ◽  
Phase Field ◽  
Thermal Gradient ◽  
Driving Forces ◽  
Phase Particle ◽  
Second Phase ◽  
Solid State Physics ◽  
Second Phase Particles ◽  
Multi Phase

AbstractUnderstanding the interaction between complex thermal fields and metallic structures at the meso-scale is crucial for the prediction of microstructural evolution during thermomechanical processing. The competitive growth of crystal grains, driven by thermodynamic forces at the grain boundaries, is one of the most fundamental phenomena in metallurgy and solid state physics. The presence of second phase particles, which act as pinning sites for boundaries, drastically alters the coarsening behaviour of the system; particularly when considering that these particles have different thermal properties to the primary phase. In this work a multi-phase field model, incorporating thermal gradient and curvature driving forces, is used to predict grain growth in a Ti6Al4V alloy system with second phase particle inclusions representative of oxide and carbide precipitates. The multi-phase field framework is fully coupled to the heat equation. The incorporation of the thermal gradient driving force enables the detailed behaviour of the grain boundaries around the particles to be predicted. It is shown that the inclusion of particles with a lower thermal conductivity has a significant influence on the coarsening behaviour of various systems of grains, due to the combined effects of thermal shielding and the generation of thermal gradient driving forces between the boundaries and pinning particles.

Phase-field Model for Diffusional Phase Transformations in Elastically Inhomogeneous Polycrystals

2011 ◽  
Vol 172-174 ◽  
pp. 1084-1089 ◽  
Author(s):  
Tae Wook Heo ◽  
Saswata Bhattacharyya ◽  
Long Qing Chen
Keyword(s):  
Grain Boundary ◽  
Phase Field ◽  
Field Model ◽  
Boundary Segregation ◽  
Phase Field Model ◽  
Transformation Process ◽  
Second Phase ◽  
Perturbation Scheme ◽  
Local Pressure ◽  
Second Phase Particles

A phase-field model is described for predicting the diffusional phase transformation process in elastically inhomogeneous polycrystals. The elastic interactions are incorporated by solving the mechanical equilibrium equation using the Fourier-spectral iterative-perturbation scheme taking into account elastic modulus inhomogeneity. A number of examples are presented, including grain boundary segregation, precipitation of second-phase particles in a polycrystal, and interaction between segregation at a grain boundary and coherent precipitates inside grains. It is shown that the local pressure distribution due to coherent precipitates leads to highly inhomogeneous solute distribution along grain boundaries.

Grain Growth of Polycrystalline AZ31 Mg Alloy Containing Second Phase Particles by Phase Field Simulation

2016 ◽  
Vol 850 ◽  
pp. 307-313
Author(s):  
Yan Wu ◽  
Si Xia ◽  
Bernie Ya Ping Zong
Keyword(s):  
Particle Size ◽  
Grain Growth ◽  
Phase Field ◽  
Phase Field Model ◽  
Free Energy Density ◽  
Critical Value ◽  
Spherical Particles ◽  
Second Phase ◽  
Pinning Effect ◽  
Second Phase Particles

A phase field model has been established to simulate the grain growth of AZ31 magnesium alloy containing spherical particles with different sizes and contents under realistic spatial-temporal scales. The expression term of second phase particles are added into the local free energy density equation, and the simulated results show that the pinning effect of particles on the grain growth is increased when the contents of particles is increasing, which is consistent with the law of Zener pinning. There is a critical particle size to affect the grain growth in the microstructure. If the size of particles is higher than the critical value, the pinning effect of particles for grain growth will be increased with further decreasing the particle size; however the effect goes opposite if the particle size is lower than the critical value.

Effect of Micro-Voids on Crack Initiation and Propagation in Bending Deformation of Al-Mg-Si Alloy Sheet

2014 ◽  
Vol 794-796 ◽  
pp. 325-330 ◽  
Author(s):  
Yusuke Yamamoto ◽  
Mineo Asano ◽  
Hideo Yoshida ◽  
Masakazu Kobayashi ◽  
Hiroyuki Toda
Keyword(s):  
Crack Initiation ◽  
Phase Particle ◽  
Shear Bands ◽  
Alloy Sheet ◽  
Second Phase ◽  
Coarse Particles ◽  
Crack Initiation And Propagation ◽  
Cube Orientation ◽  
Second Phase Particles ◽  
Initiation And Propagation

The crack initiation and propagation during bending have been considered to be affected by second phase particles, micro-voids and shear-bands. However, the effects of the second phase particles and the micro-voids on the crack initiation and propagation during bending have not been fully investigation. In this study, the effect of the second phase particle distribution on the formation of micro-voids, and the effect of the micro-voids on the crack initiation and propagation during bending were investigated using the largest synchrotron radiation facility “SPring-8” and FE-SEM/EBSD. With the bending ratio increasing, the micro-voids increased around the coarse particles near the outer surface. In particular, coarse micro-voids were formed around coarse particles with a high aspect ratio on the shear-bands. At a large cracked part, coarse micro-void was observed at the outmost layer section as a crack initiation site, and coarse micro-voids and asheared fracture surface were observed at the crack propagation site. At the small cracked part with no propagation, cube orientation grains were located under the small crack. It was considered that these cube orientation grains inhibited the formation of shear-bands, therefore, propagation of the cracks did not occur at the small cracked area.

Particle Pushing during Solidification of Metals and Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 1513-1517 ◽  
Author(s):  
Meng Wang ◽  
Qin You Han
Keyword(s):  
Alloy System ◽  
Liquid Interface ◽  
Second Phase ◽  
Matrix Composites ◽  
Freezing Front ◽  
Cooling Conditions ◽  
Second Phase Particles ◽  
Solid Liquid Interface ◽  
Particle Pushing ◽  
Solid Liquid

During the solidification of a liquid containing dispersed second phase particles, particles are either rejected or engulfed by the advancing solid-liquid interface. Theories have been proposed on the mechanisms on particle pushing by a freezing front. However, the critical growth velocities predicted are much smaller than actually found experimentally. This article evaluates mechanisms on particle pushing. A specially selected alloy system, an Al-Ti-B master alloy, was chosen to evaluate particle pushing under various solidification conditions. The final distribution of the particles in ingots was examined. It is concluded that most of the particles are pushed by the dendritic solid liquid interface under cooling conditions varying a few orders of magnitude. Mechanical disturbance, such as fluid flow in the remaining liquid of the mushy zone, promotes particle pushing by the growing solid. Keywords: Particle pushing, solidification, Aluminum alloys, and metal-matrix composites

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