Microstructural Evolution in Interdiffusion Zone and Its Effect on Diffusion Path K. Wu, J. E. Morral and Y. Wang Department of Materials Science and Engineering The Ohio State University Work Supported by NSF TMS05 Annual Meeting Feb. 13-17, 2005, San Francisco, California
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Microstructural Evolution in InterdiffusionZone and Its Effect on Diffusion Path
K. Wu, J. E. Morral and Y. Wang
Department of Materials Science and EngineeringThe Ohio State University
Work Supported by NSFTMS05 Annual Meeting
Feb. 13-17, 2005, San Francisco, California
Experimental Observation of InterdiffusionMicrostructure and Diffusion Path
Xin Qiao. M.S. Thesis. University of Connecticut. 1998
Exp. Observation by Nesbitt and Heckel in Met Trans. A (1986)18A: 2087-2094
ExperimentalData
ExperimentalData
MobilityDatabase Mobility
Database
TDDatabase
TDDatabase
Chemical Diffusivity of Al
Thermodynamic description
Phase Field
Interface Properties
Interface Properties
Elastic PropertiesElastic
Properties
Other properties
Database development
Atomistic CalculationsAtomistic
Calculations
DICTRA DICTRA
Thermo_Calc or PANDAT
Thermo_Calc or PANDAT
DICTRA
Phase FieldModel
γ-surfacesγ-surfaces
Optimizer
Constitutiveequation
construction
Constitutiveequation
construction
Phase field model
development
Kinetic description
Linking to Thermo. and Kinetic Databases and Atomistic Calculations
Scripta mater. 50(2004)471-476; ibid,50(2004)1145-1150
Quantitative comparison with DICTRA
Dissolution
Growth
Q. Chen et. al. Scripta mater. 50 (2004)471-476
Exp. Observation by Nesbitt and Heckel
Interdiffusion Microstructure and Diffusion Path0 hr
4 hr
25 hr
320µm
100 hrat 1200oC
Ni-Al-Cr at 1200oC
• Free energy data from Huang and Chang
• Mobilities in γ from A.EngstrÖm and J.Ågren
• Diffusivities in β from Hopfe, Son, Morral and Roming
• Free energy data from Huang and Chang
• Mobilities in γ from A.EngstrÖm and J.Ågren
• Diffusivities in β from Hopfe, Son, Morral and Roming
200µm
XCr =0.25, XAl=0.001
γ+β < γ
Annealing time: 25 hours
(a)
(b)
(c)
Effect of Cr content on interface migrationEffect of Cr content on interface migration
320µm
Ni-Al-Cr at 1200oC
(d)
b ca d
γ+β < γ
Exp. measurement by Nesbitt and Heckel
Diffusion path and recess rate -comparison with experiment
Diffusion path and recess rate -comparison with experiment
Annealing time: 25 hours
(a)
(b)
(c)
Effect of Al content on interface migrationEffect of Al content on interface migration320µm
a
cb
c
γ+β < γ
Annealing time: 25 hours
(a)
(b)
Effect of Al content on interface migrationEffect of Al content on interface migration
320µm
ab
γ+β > γ
γ+β < γ
Shape of the Diffusion Path
t = 0
t = 25h
t = 100h pure coarseningγ+β > γ
500µm
β- γ+
Shape of Diffusion Path - Comparison with DICTRA
0.15
0.20
0.10
γ+β
γ
A.EngstrÖm, J. E. Morral and J.ÅgrenActa mater. 1997
Growth vs. Nucleation
γ+β > γγ+β < γ
Summary – Remaining Challenges
• Incorporation of nucleation• Breaking the intrinsic length scale limit of quantitative
phase field modeling- effect of surface energy, e.g.,
coarsening and coalescence
• Quantitative comparison with experiment- accuracy of thermodynamic and mobility databases- accurate determination of average composition of multiphase
microstructure in both simulation and experiment- Accurate determination of boundary position
c
η
C. Shen et al., Scripta mater. (2004) 50:1023-1028; ibid, 1029-1034.