Molecular dynamics study on radiation hardening and fracture processes

in FCC metals

Molecular dynamics study on radiation hardening and fracture processes

in FCC metals

Hideo Kaburaki (JAERI)

DOE Workshop on Advanced Computational Materials Science, 31 Mar.-2 Apr.,2004

6.39-7.15×10-6Å/step

（3.20-3.58×10-2Å/10ps）　

For 80ps (40,000steps)・(111)

Effect of external shear stress for unfaulting

[111]

x

Ｚ

]110[Ｙ

[112]Shear strain

nearly 380,000 atoms

pure alminium

Interatomic potential : Embedded-atom method (EAM) potential　　　　　　　　　　[Y. Mishin et al., PRB (2001).]

Unfaulting process of H721 vacancy loop

Partial dislocation loop

Coordination number representation

Central symmetry parameter representation

Stacking fault

Results of unfaulting critical shear stress

for vacancy loops

Intrinsic stacking fault

[111]

Number of atoms　3.8×105

170Å

120Å

200Å

x

Ｚ

]110[

Ｙ

10Å

mixed free

periodic

Hardening process Hardening process ------ the interaction of an edge the interaction of an edge dislocation with a hexagonal interstitial dislocation loopdislocation with a hexagonal interstitial dislocation loop

Simulation SystemSimulation System[112]

Interatomic potential : Embedded-atom method (EAM) potential　　Cu, Al　　　　　[Y. Mishin et al., PRB (2001).]

( )iiij

ijtot ρFrVE ∑∑ += )(21 V: Pair potential

F: Embedding energy

Pinning structure formed due to the interaction of an edge dislocation and an interstitial cluster in Cu

H007 H037 H169 H721

Pinning structure formed due to the interaction of an edge dislocation and an interstitial cluster in Al

H007 H037 H169 H721

A molecular dynamics study on displacement cascades in the strain field of an edge dislocation in Cu

Movie1Movie2Movie3

40Å

[110]1kev

Movieat 300K

205×177×125Å

FractureFracture process process ------ developmentdevelopment of crackof crack--tiptipmicrostructuresmicrostructures

ModeⅠcrack in asingle fcc crystal

ModeⅠcrack in asingle fcc crystal

# of atoms： 1,036,960

291.5 Å

291.

5 Å

144.6Å

xy

]110[]011[

z ]001[

CoordinateCoordinatesystemsystem

Simulation CellSimulation Cell

Slip plane = {111}The slip planes and the (110) crack plane intersect obliquely

at 70.5°x ½

Temperature dependence on the crack-tip dislocation nanostructures (Cu)

24 ps

150 K0 K 50 K 300 K

16 ps

Initial crack length

DislDisl. motion on the slip plane (Cu, 50K). motion on the slip plane (Cu, 50K)

16 16 psps 18 18 psps 20 20 psps 22 22 psps

24 24 psps 26 26 psps 28 28 psps 30 30 psps

]121[

]112[0]1[1

AlCu

Expansion and emission process ofExpansion and emission process ofstackingstacking--fault loopsfault loops

fcc

hcp

fcc

hcp

fcc

Shockley partial

11261

C.N. = 10 : Green11 : Red12 : omitted (f.c.c.) 13 : Blue

18.4 ps

21.6 ps

10.0 ps