Atomic-Scale Computer Simulation of Mixture Precipitation Mechanism for Ni75AlxV25-x Alloy

2005 ◽  
Vol 475-479 ◽  
pp. 3115-3118 ◽  
Author(s):  
Yu Hong Zhao ◽  
Dong Ying Ju ◽  
Hua Hou
Keyword(s):  
Computer Simulation ◽  
Spinodal Decomposition ◽  
Field Model ◽  
Phase Field Model ◽  
Nucleation And Growth ◽  
Atomic Scale ◽  
Precipitation Mechanism ◽  
Ordered Phases ◽  
Nucleation And Growth Mechanism ◽  
Microscopic Phase Field Model

With the microscopic phase-field model, the early precipitation mechanisms of the ternary Ni75AlxV25-x alloys with middle Al composition were explored by computer simulation in this paper. Through the simulated atomic pictures and composition order parameters of precipitates, we can explain the complex precipitation mechanisms of θ (Ni3V) and γ′ (Ni3Al) ordered phases. Simulated results also show that the precipitation characteristic of γ′ phase transforms from non-classical nucleation and growth to congruent ordering + Spinodal decomposition gradually, otherwise, the precipitation characteristic of θ phase transforms from congruent ordering + Spinodal decomposition to non-classical nucleation and growth mechanism gradually.

Atomic-Scale Computer Simulation for early Precipitation Process of Ni75AlXV25-X Alloy with Middle Al Composition

2011 ◽  
Vol 704-705 ◽  
pp. 1328-1337
Author(s):  
Yu Hong Zhao ◽  
Hua Hou ◽  
Yu Hui Zhao
Keyword(s):  
Spinodal Decomposition ◽  
Volume Fraction ◽  
Transition Process ◽  
Nucleation And Growth ◽  
Atomic Scale ◽  
Precipitation Process ◽  
Atom Fraction ◽  
Precipitation Mechanism ◽  
Al Content ◽  
Ordered Phases

The microscopic phase field approach was applied for modeling the early precipitation process of Ni75AlxV25-xalloy. Without any a prior assumption, this model can be used to simulate the temporal evolution of arbitrary morphologies and microstructures on atomic scale. Through the simulated atomic pictures, calculated order parameters and volume fraction of the θ (Ni3V) and γ′ (Ni3Al) ordered phases, Ni75AlxV25-xalloys with Al composition of 0.05, 0.053 and 0.055 (atom fraction) were studied. Results show: For these alloys, θ and γ′ precipitated at the same time. With the increase of Al content, the amount of γ′ phase is increasing and that of θ phase is decreasing; the precipitation characteristic of γ′ phase transforms from Non-Classical Nucleation and Growth (NCNG) to Congruent Ordering + Spinodal Decomposition (CO+SD) gradually, otherwise, the precipitation characteristic of θ phase transforms from Congruent Ordering + Spinodal Decomposition (CO+SD) to Non-Classical Nucleation and Growth (NCNG) mechanism gradually. Both θ and γ′ has undergone the transition process of mixture precipitation mechanism with the characteristic of both NCNG and CO+SD mechanism. No incontinuous transition of precipitation mechanism has been found.

Microscopic Phase-Field Simulation of the Process of Middle Heat Treatment of Ni-Cr-Al Alloy

2011 ◽  
Vol 80-81 ◽  
pp. 36-39
Author(s):  
Zhong Chu ◽  
Guo Qun Zhao
Keyword(s):  
Heat Treatment ◽  
Phase Field ◽  
Field Model ◽  
Volume Fraction ◽  
Phase Field Model ◽  
Nucleation And Growth ◽  
Al Alloy ◽  
Precipitation Mechanism ◽  
Microscopic Phase Field Model ◽  
Strengthening Phases

The effect of the middle heat treatment+aging(1323K+1073K) for the precipitation mechanism and volume fraction of Ni-11at.%Cr-17at.%Al ternary alloy are studied based on microscopic phase-field model. The results show that the precipitation mechanism is non-classical nucleation and growth for the alloy at middle heat treatment, and the congruent ordering and spinodal decomposition mechanism occur at single-stage aging. The larger precipitation strengthening phases are obtained, the volume fraction of ordering phases and the averaged ordering parameter are higher, and the incubation period prolongs after the middle heat treatment.

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.

A Phase Field Approach for Modeling Melting and Re-Solidification of Ti-6Al-4V during Selective Laser Melting

2016 ◽  
Vol 704 ◽  
pp. 241-250 ◽  
Author(s):  
Peter Holfelder ◽  
Jin Ming Lu ◽  
Christian Krempaszky ◽  
Ewald A. Werner
Keyword(s):  
Selective Laser Melting ◽  
Phase Field ◽  
Field Model ◽  
Phase Field Model ◽  
Nucleation And Growth ◽  
Laser Melting ◽  
Laser Material ◽  
Field Approach ◽  
Multi Phase ◽  
Material Interaction

A Multi Phase Field model is proposed to describe the microstructure evolution induced by laser-material interaction in Selective Laser Melting (SLM). On the basis of the free enthalpy, the nucleation and growth processes occurring during the relevant phase transformations are explicitly taken into account. Within this contribution, the focus is laid on the SLM processing of the titanium alloy Ti-6Al-4V with special emphasis on the transition between β-titanium and melt. The results are discussed and compared to those of more conventional modelling approaches.

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.

Surface Stress Effects on the Elastic Behavior of Nanoporous Metals

2005 ◽  
Vol 900 ◽  
Author(s):  
Douglas A. Crowson ◽  
Diana Farkas ◽  
Sean G. Corcoran
Keyword(s):  
Computer Simulations ◽  
Surface Stress ◽  
Field Model ◽  
Phase Field Model ◽  
Atomic Scale ◽  
Elastic Behavior ◽  
Stress Effects ◽  
Macroscopic Deformation ◽  
Nanoporous Metals ◽  
Nanoporous Structures

ABSTRACTAtomic scale computer simulations were used to investigate the surface stress induced deformation in nanoporous metals. A phase field model was used to generate digital nanoporous structures that are quantitatively similar to those created experimentally via dealloying. We analyze the important effects of surface relaxations on the macroscopic deformation in these samples as well as in small spherical clusters.

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