Kinetics of Order-Disorder Transition of Antiphase Domain Boundary Formed between DO22 Phases: Microscopic Phase-Field Study

2010 ◽  
Vol 160-162 ◽  
pp. 996-1000
Author(s):  
Ming Yi Zhang ◽  
Kun Yang ◽  
Zheng Chen
Keyword(s):  
Phase Field ◽  
Domain Boundary ◽  
Phase Field Model ◽  
Antiphase Domain ◽  
Precipitation Process ◽  
Second Phase ◽  
Phase Layer ◽  
Disorder Transition ◽  
Disordered Phase ◽  
Kinetics Of

Based on the microscopic phase-field model, the precipitation process of Ni75Al4.3V20.7 alloy at 1190K is simulated, and the kinetics of order-disorder transition at antiphase domain boundary (APDB) formed between DO22 (Ni3V) phases is investigated. After the ordered APDB formed by the impingement of growing DO22 (Ni3V) domains, the order-disorder transition at APDB is happened. Accompanied with the enrichment of Ni and Al at the APDB, the ordered APDB transforms into a thin disordered phase layer. The second phase L12 nucleates at the order-disorder interface between DO22 and disordered phases, and grows along the disorder phase layer quickly. The order-disorder transition at the ordered APDB accelerates the nucleation and growth of L12 phase at the APDB. The disordered phase caused by the order-disordered transition can be considered the transient phase during the precipitation process of L12 phase.

Microscopic Phase-Field Simulation of the Order-Disorder Transition of Antiphase Domian Boundary Formed between DO22 Phases

2010 ◽  
Vol 44-47 ◽  
pp. 3736-3740
Author(s):  
Ming Yi Zhang ◽  
Kun Yang ◽  
Zheng Chen
Keyword(s):  
Phase Field ◽  
Domain Boundary ◽  
Phase Field Model ◽  
Antiphase Domain ◽  
Precipitation Process ◽  
Second Phase ◽  
Phase Layer ◽  
Disorder Transition ◽  
Disordered Phase ◽  
Microscopic Phase Field Model

The order-disorder transition at antiphase domain boundary (APDB) between DO22 (Ni3V) phases is investigated using the microscopic phase-field model. After the formation of ordered APDB, the order-disorder transition at APDB is happened, and the ordered APDB transforms into a thin disordered phase layer. Accompanied with the enrichment of Ni and Al at the disordered APDB, the second phase L12 nucleates at the order-disorder interface between DO22 phases and grows along the disordered phase layer. The order-disorder transition at the ordered APDB makes the nucleation and growth of the second phase L12 much easier and faster. The disordered phase caused by the order-disorder transition at the APDB can be considered as the transient phase during the precipitation process of L12 phase.

Microscopic Phase Field Study on the Kinetics of Order-Disorder Transition of APDBs Formed between DO22 Phases during Stress Aging

2014 ◽  
Vol 789 ◽  
pp. 530-535 ◽  
Author(s):  
Ming Yi Zhang ◽  
Guang Quan Yue ◽  
Jia Zhen Zhang ◽  
Kun Yang ◽  
Zheng Chen
Keyword(s):  
Phase Field ◽  
Field Model ◽  
Domain Boundary ◽  
Phase Field Model ◽  
Antiphase Domain ◽  
Phase Layer ◽  
Disorder Transition ◽  
Disordered Phase ◽  
Kinetics Of ◽  
Microscopic Phase Field Model

Kinetics of order-disorder transition at antiphase domain boundary (APDB) formed between DO22 (Ni3V) phases during stress aging was investigated using microscopic phase field model. The results demonstrated that whether order-disorder transition happens or not depends on the atomic structure of the APDB. Accompanied with the depletion of V and enrichment of Ni and Al, order-disorder transition happened at the APDB (001)//(002). Whereas at the APDB {100}·1⁄2[100], which remains ordered with temporal evolution, Ni and Al enrich and V depletes. Composition evolution of APDB with order-disorder transition favors the nucleation of the L12 and disordered phase. Some of the grains grew bigger while the others disappeared, accompanying the formation of disordered phase layer during order-disorder transition of APDBs, and the order-disorder transition of APDBs can be considered as accompanying process of coarsening of ordered domain phases and growth of disordered phases.

Microscopic phase-field study on order-disorder transition of the antiphase domain boundary formed between L12 phases

2011 ◽  
Vol 54 (12) ◽  
pp. 3409-3414 ◽  
Author(s):  
MingYi Zhang ◽  
Kun Yang ◽  
Zhen Chen ◽  
YongXin Wang ◽  
XiaoLi Fan
Keyword(s):  
Field Study ◽  
Phase Field ◽  
Domain Boundary ◽  
Antiphase Domain ◽  
Disorder Transition

Phase Field Model for Influence of Edge Dislocation on Precipitation

2011 ◽  
Vol 415-417 ◽  
pp. 1482-1485
Author(s):  
Chuang Gao Huang ◽  
Ying Jun Gao ◽  
Li Lin Huang ◽  
Jun Long Tian
Keyword(s):  
Edge Dislocation ◽  
Phase Field ◽  
Field Model ◽  
Phase Field Model ◽  
Field Method ◽  
Phase Field Method ◽  
Second Phase ◽  
Free Energy Function ◽  
Phase Nucleation ◽  
Good Agreement

The second phase nucleation and precipitation around the edge dislocation are studied using phase-field method. A new free energy function is established. The simulation results are in good agreement with that of theory of dislocation and theory of non-uniform nucleation.

Computer Simulation of Evolution of Ordering Phases and the Boundaries of Ni-Cr-Al Alloy

2011 ◽  
Vol 233-235 ◽  
pp. 1782-1785
Author(s):  
Zhong Chu ◽  
Guo Qun Zhao
Keyword(s):  
Computer Simulation ◽  
Long Range ◽  
Phase Field ◽  
Field Model ◽  
Phase Field Model ◽  
Range Order ◽  
Precipitation Process ◽  
Al Alloy ◽  
Long Range Order

Based on the microscope phase-field model，the evolution of atom morphology, the long range order(lro) parameter and concentration can be gotten, and atomic clustering and ordering during the precipitation process of Ni-Cr-Al alloy could be obtained. The Ni-14at.%Cr-15.5at.%Al alloy is studied and the temperature of precipitation are 973K. It was showed that the ordering of both Al and Cr atoms take place simultaneously during the precipitation process of Ni-Al-Cr alloy, Cr atoms transfer to the boundaries of L12phases, the domain of rich Cr atoms are formed. At the boundaries of L12phases, Cr atoms may substitute the Al sublattice, and the D022phases are formed.

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.

The Simulation of Stress-Induced Phase Transition of L10 Re-Precipitation Based on Microscopic Phase-Field Model

2011 ◽  
Vol 689 ◽  
pp. 226-234
Author(s):  
Yong Xin Wang ◽  
Yong Biao Wang ◽  
Zheng Chen ◽  
Yan Li Lu
Keyword(s):  
Phase Transition ◽  
Induction Period ◽  
Phase Field ◽  
Field Model ◽  
Large Range ◽  
Phase Field Model ◽  
Precipitation Process ◽  
Phase Precipitation ◽  
Microscopic Phase Field Model ◽  
Precipitation Phase

It is common that the pre-precipitation phase with kinetics advantage is found during non-equilibrium transformation. The continuously changed stress in the transformation increases the complication of precipitation process. The stress induces Ll0pre-precipitation phase in Ni75-Al12.5-V12.5alloy is studied by microscope phase-field model in this paper. It is particularly show that Ll2phase precipitates directly without stress. There is no Ll0phase to be found in the disordered matrix. Oppositely, Ll0phase precipitates firstly with stress, and then it turns into Ll2phase. When stress is less, either or both above situations are observed. While stress is stronger, a large range of Ll0phase precipitates firstly. Then a part of it dissolves. The rest turns into Ll2phase. The precipitation of pre-precipitation phase accelerates the precipitation process. The larger the stress and the more Ll0phase precipitation, the longer it exists and the shorter the induction period is.

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.

STRUCTURE OF Cu-Au ALLOY NANOSCALE PARTICLES AND THE PHASE TRANSFORMATION

1996 ◽  
Vol 03 (01) ◽  
pp. 65-69 ◽  
Author(s):  
T. TADAKI ◽  
A. KOREEDA ◽  
Y. NAKATA ◽  
T. KINOSHITA
Keyword(s):  
Phase Transformation ◽  
Domain Boundary ◽  
High Resolution Electron Microscopy ◽  
Antiphase Domain ◽  
Minimum Size ◽  
Nominal Composition ◽  
Disorder Transition ◽  
Nanoscale Particles ◽  
Superlattice Structure ◽  
Alloy Particles

Atomic structure of nanoscale particles of a Cu-Au alloy with a nominal composition Cu3Au and the phase transformation therein are studied by means of high-resolution electron microscopy and electron diffraction. The particles 8.8 nm in diameter on average prepared by simultaneous vacuum deposition of the constituent elements exhibit as a whole an fcc structure of an alloy with a composition of 26.4 at.% Au. The alloy particles are ordered into the L12-type superlattice structure when heat-treated at 563 K for 1 h. The superlattice reflections disappear upon heating up to 773 K. In a particle about 10 nm in size an antiphase domain boundary is observed. It thus appears that the nanoscale particles of the alloy undergo the order-disorder transition, as in the bulk. However, the critical temperature Tc for the order-disorder transition of the nanoscale particles is found to be by about 90 K lower than that of the bulk. The minimum size of the alloy particles in which lattice fringes whose spacing corresponds to the interplanar spacing of the {100}-type superlattice planes are observed is about 4 nm. These facts suggest that a certain critical size and size effects are present for atomic ordering in the Cu-Au alloy particles.

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