Effect of alloying solute atoms
and carbon on helium in -Fe
Yange Zhang, Yuwei You, Yichun Xu, C.S.Liu
[email protected]
Institute of Solid State Physics,
Chinese Academy of Sciences, PR China
2016/7/27
1
Outline
Background and motivation
Computational method
Main results
2016/7/27
2
Background and motivation
Nucl.Fusion.,24(1984)1039
Segregation of He could be precursors for
He bubbles which degrade the mechanical
properties of steel.
It is crucial to mitigate the growth of He
bubbles in steel.
2016/7/27
J.Nucl.Mater.318(2003)249
3
Background and motivation
 He bubble comes from the attraction between He and vacancy
or He.
 The solutes could prevent the outburst of large bubbles by
providing many traps leading to the formation of very many
2016/7/27
4
small clusters rather than few large ones.
Computational method
• Density functional theory-VASP software
• GGA-PBE
• Ecut: 500eV
• Supercell: 128 atoms(11.33*11.33*11.33Å3)
• Binding energy
Eb=Et(A)+Et(B)-Et(A+B)-E0t, Eb>0, attraction
Eb<0, repulsion
2016/7/27
5
Main results--interaction between common solutes and He
The sp solutes bind with He more strongly than TM solutes.
2016/7/27
6
Main results--interaction between sp solutes and He
The interaction between He and other sp solutes?
2016/7/27
7
Main results--interaction between sp solutes and He
1nn
3nn
2nn
1nn
Sol
Sol
3nn
2nn
The binding energies between solutes and He(sub) are
much stronger than that of He(TS).
2016/7/27
8
Main results--interaction between sp solutes and C
What the effect of carbon on the interaction between
solutes and He?
1nn
Sol
3nn
2nn
 All the considered solutes are repusive with carbon.
2016/7/27
9
Main results--dependence of Eb on the solute size factor
 The Solute-He(sub)
attraction and Solute-C
repulsion increase with
the size factor of solutes.
 The Solute-He attraction
mainly comes from the
interaction of the solute
with the vacancy
occupied by the He.
Volume
difference:
2016/7/27
V  V (Fe127Sol )  V (Fe128 )
10
Main results--interaction between C and He
7
5
4
9
2
C
1
4
1
6
3
8
Eb(C-He)~0.08eV(site3)
C
3
2
5
Eb(C-He)~0.32eV(site1)
 Different tetrahedral and substitutional sites of He around
C are examined to find the interaction between C and He.
 There is weak repulsion between C and He(TS), but weak
attraction between C and He(sub).
2016/7/27
11
Main results--stability of C-Sol-He complex
He
Fe
Sol
C
 Considering the attraction of Sol-He(sub) and C-He(sub),
different sites of C around Sol-He(sub) are examined to
find the most stable configuration of C-Sol-He complex.
 C-Sol-He(sub) complex can be formed stably in iron.
2016/7/27
12
Conclusion
Substitutional helium shows more attractive than interstitial helium to the sp solutes.
carbon‐solute‐helium complex can be formed stably in iron and carbon could enhance the attraction of the complex to He, especially for C‐
S‐He complex.
2016/7/27
13
Thanks for your attention!
2016/7/27
14