Table 1 Summary of experimental observations and comparisons with simulated results. Grain boundaries were extracted and analysed from seven different samples.

From: Role of disordered bipolar complexions on the sulfur embrittlement of nickel general grain boundaries

 

GB (Ă—Facets)

Annealing T (Teutectic = 650 °C)

Observed type

Orientation relationship

Thickness h (nm)

Measured adsorption Γ (S atoms/nm2)

Simulation GB model

Simulated type

Simulated adsorption Γ (S atoms/nm2)

Simulated results shown in

 

#1A × 8

675 °C

A

(100)//~(532)~1° off

0.92 ± 0.17

34.9

(100)//(926)

A

23.9

Fig. 3

#1B × 2

675 °C

B

(310)//~(744) ~1° off

<0.3

12.6

(310)//(457)

B

12.1

Supp. Fig. 42

#1B × 2

(310)//(3\(\bar 1\)0)

B

12.2

Supp. Fig. 43

 

#2A × 2

675 °C

A

(100)//~(7 11 11)

0.78 ± 0.06

 

(100)//(926)

A

23.9

Fig. 3

 

#3A × 5

675 °C + 575 °C

A

(100)//~(211) ~1° off

0.89 ± 0.14

15.4

 

#3B × 6

675 °C + 575 °C

B

(311)//~(511) ~3° off

<0.4

12.6

    
 

#4A × 3

575 °C

A

(100)//~(320) ~6° off

0.80 ± 0.13

24.6

(100)//(926)

A

23.9

Fig. 3

 

#4B × 2

575 °C

B

(211)//~(403) ~3° off

<0.4

6.2

    
 

#5B × 4

500 °C

B

(110)//~(331) ~2° off

<0.3

7.0

(110)//(345)

B

9.63

Fig. 4

 

#6C

675 °C + 575 °C

C

(111)//(111) Twin

~0

~0

(111)//(111) Twin

C

~0

Supp. Fig. 44

 

#7C

675 °C + 575 °C

C

(111)//(111) Twin

~0

~0

(111)//(111) Twin

C

~0

Supp. Fig. 44

 

#8C

575 °C

C

Low-angle GB

~0

~0

    
 

#9C

500 °C

C

(111)//(111) Twin

~0

~0

(111)//(111) Twin

C

~0

Supp. Fig. 44

 

#10C

500 °C

C

(111)//(111) Twin

~0

~0

(111)//(111) Twin

C

~0

Supp. Fig. 44

  1. In this study, we examined 34 independent GBs or GB facets, including: (A) 18 independent GB facets that have one lower-index terminal grain surface of the (100) plane with another higher-index matching grain surface, which were all found to be Type A (amorphous-like); (B) 11 GB facets (and 14 independent locations) that have one lower-index grain surface of the (310), (311), (211), or (110) plane with another higher-index matching grain surface, which were all found to be Type B (bilayer-like); and (C) 5 GBs are nominally clean (Type C), where four were found to be Σ3 (111)//(111) symmetric twin boundaries and another was determined to be a low-angle GB. The results clearly suggest the formation of complexions correlated with the orientation of the lower-index grain terminating plane, instead of the misorientation. Thus, in the semi-grand-canonical-ensemble atomistic simulations, we selected one grain of the GB model to match exactly the lower-Miller-index plane observed in the experiment, while the other grain was chosen to be similar (but not identical) to that observed in the experiment to allow the application of a periodic condition. As an example of the notations used in Column 1, “#1A × 8” means that eight independent (disconnected), parallel facets on GB #1 were examined and all eight were Type A. Noting that GB #5B is flat and long; we examined four different locations that were far apart, all of which were Type B. See Supplementary Note 20 and Supplementary Table 3 for a critical comparison of simulation and experiments.
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