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Dislocation-twin boundary interactions induced nanocrystalline via SPD processing in bulk metals.

Zhang F, Feng X, Yang Z, Kang J, Wang T - Sci Rep (2015)

Bottom Line: This report investigated dislocation-twin boundary (TB) interactions that cause the TB to disappear and turn into a high-angle grain boundary (GB).The evolution of the microstructural characteristics of Hadfield steel was shown as a function of severe plastic deformation processing time.These reactions induced atomic steps on the TB and led to the accumulation of gliding dislocations at the TB, which resulted in the transition from coherent TB to incoherent GB.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.

ABSTRACT
This report investigated dislocation-twin boundary (TB) interactions that cause the TB to disappear and turn into a high-angle grain boundary (GB). The evolution of the microstructural characteristics of Hadfield steel was shown as a function of severe plastic deformation processing time. Sessile Frank partial dislocations and/or sessile unit dislocations were formed on the TB through possible dislocation reactions. These reactions induced atomic steps on the TB and led to the accumulation of gliding dislocations at the TB, which resulted in the transition from coherent TB to incoherent GB. The factors that affect these interactions were described, and a physical model was established to explain in detail the feasible dislocation reactions at the TB.

No MeSH data available.


Related in: MedlinePlus

Nanocrystalline boundary structure of sample surface subjected to HSP for 8 × 104 times: (a) equiaxed nanocrystalline; (b) a close view of area “b” in Fig. 1(a); (c) a close view of area “c” in Fig. 1(a) and corresponding fast Fourier-transformed image in a black rectangular box; (d) inverse fast Fourier-transformed image of area “d” in Fig. 1(c).
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f1: Nanocrystalline boundary structure of sample surface subjected to HSP for 8 × 104 times: (a) equiaxed nanocrystalline; (b) a close view of area “b” in Fig. 1(a); (c) a close view of area “c” in Fig. 1(a) and corresponding fast Fourier-transformed image in a black rectangular box; (d) inverse fast Fourier-transformed image of area “d” in Fig. 1(c).

Mentions: A nanocrystalline surface layer formed after HSP was performed 8 × 104 times (Fig. 1). A close view of area “b” in Fig. 1(a) reveals the presence of several dislocations and the absence of twinning, as shown in Fig. 1(b). HRTEM observation (Fig. 1c) on the boundary between adjacent nanograins was performed to clarify dislocation–TB interactions. The green lines indicate the location of () planes on both sides of a () TB. Two grains in the nanoscale share a twin relationship, as indicated by the fast Fourier-transformed image in Fig. 1(c). The results reveal that the feasible dislocation–TB interactions cause the TB to disappear and turn into a grain boundary (GB) during nanocrystallization. Fig. 1(d) shows the inverse fast Fourier-transformed image of area “d” in Fig. 1(c). As shown in the area, the presence of the curved TB is associated with some unit dislocations. Meanwhile, multiple dislocation tangles or stacking faults occur around the TB, leading to the transition from coherent TB to incoherent high-angle GB.


Dislocation-twin boundary interactions induced nanocrystalline via SPD processing in bulk metals.

Zhang F, Feng X, Yang Z, Kang J, Wang T - Sci Rep (2015)

Nanocrystalline boundary structure of sample surface subjected to HSP for 8 × 104 times: (a) equiaxed nanocrystalline; (b) a close view of area “b” in Fig. 1(a); (c) a close view of area “c” in Fig. 1(a) and corresponding fast Fourier-transformed image in a black rectangular box; (d) inverse fast Fourier-transformed image of area “d” in Fig. 1(c).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4355667&req=5

f1: Nanocrystalline boundary structure of sample surface subjected to HSP for 8 × 104 times: (a) equiaxed nanocrystalline; (b) a close view of area “b” in Fig. 1(a); (c) a close view of area “c” in Fig. 1(a) and corresponding fast Fourier-transformed image in a black rectangular box; (d) inverse fast Fourier-transformed image of area “d” in Fig. 1(c).
Mentions: A nanocrystalline surface layer formed after HSP was performed 8 × 104 times (Fig. 1). A close view of area “b” in Fig. 1(a) reveals the presence of several dislocations and the absence of twinning, as shown in Fig. 1(b). HRTEM observation (Fig. 1c) on the boundary between adjacent nanograins was performed to clarify dislocation–TB interactions. The green lines indicate the location of () planes on both sides of a () TB. Two grains in the nanoscale share a twin relationship, as indicated by the fast Fourier-transformed image in Fig. 1(c). The results reveal that the feasible dislocation–TB interactions cause the TB to disappear and turn into a grain boundary (GB) during nanocrystallization. Fig. 1(d) shows the inverse fast Fourier-transformed image of area “d” in Fig. 1(c). As shown in the area, the presence of the curved TB is associated with some unit dislocations. Meanwhile, multiple dislocation tangles or stacking faults occur around the TB, leading to the transition from coherent TB to incoherent high-angle GB.

Bottom Line: This report investigated dislocation-twin boundary (TB) interactions that cause the TB to disappear and turn into a high-angle grain boundary (GB).The evolution of the microstructural characteristics of Hadfield steel was shown as a function of severe plastic deformation processing time.These reactions induced atomic steps on the TB and led to the accumulation of gliding dislocations at the TB, which resulted in the transition from coherent TB to incoherent GB.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.

ABSTRACT
This report investigated dislocation-twin boundary (TB) interactions that cause the TB to disappear and turn into a high-angle grain boundary (GB). The evolution of the microstructural characteristics of Hadfield steel was shown as a function of severe plastic deformation processing time. Sessile Frank partial dislocations and/or sessile unit dislocations were formed on the TB through possible dislocation reactions. These reactions induced atomic steps on the TB and led to the accumulation of gliding dislocations at the TB, which resulted in the transition from coherent TB to incoherent GB. The factors that affect these interactions were described, and a physical model was established to explain in detail the feasible dislocation reactions at the TB.

No MeSH data available.


Related in: MedlinePlus