scholarly journals Formation of incoherent deformation twin boundaries in a coarse-grained Al-7Mg alloy

2015 ◽  
Vol 107 (9) ◽  
pp. 091901 ◽  
Author(s):  
S. B. Jin ◽  
K. Zhang ◽  
R. Bjørge ◽  
N. R. Tao ◽  
K. Marthinsen ◽  
...  
Keyword(s):  
Deformation Twin ◽  
Coarse Grained ◽  
Twin Boundaries

scholarly journals Investigating the dislocation reactions on Σ3{111} twin boundary during deformation twin nucleation process in an ultrafine-grained high-manganese steel

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chang-Yu Hung ◽  
Tomotsugu Shimokawa ◽  
Yu Bai ◽  
Nobuhiro Tsuji ◽  
Mitsuhiro Murayama
Keyword(s):  
Grain Boundary ◽  
Twin Boundary ◽  
Deformation Twin ◽  
Coarse Grained ◽  
Manganese Steel ◽  
High Manganese ◽  
Twin Boundaries ◽  
Dominant Type ◽  
Twin Nucleation ◽  
Ultrafine Grained

AbstractSome of ultrafine-grained (UFG) metals including UFG twinning induced plasticity (TWIP) steels have been found to overcome the paradox of strength and ductility in metals benefiting from their unique deformation modes. Here, this study provides insights into the atomistic process of deformation twin nucleation at Σ3{111} twin boundaries, the dominant type of grain boundary in this UFG high manganese TWIP steel. In response to the applied tensile stresses, grain boundary sliding takes place which changes the structure of coherent Σ3{111} twin boundary from atomistically smooth to partly defective. High resolution transmission electron microscopy demonstrates that the formation of disconnection on Σ3{111} twin boundaries is associated with the motion of Shockley partial dislocations on the boundaries. The twin boundary disconnections act as preferential nucleation sites for deformation twin that is a characteristic difference from the coarse-grained counterpart, and is likely correlated with the lethargy of grain interior dislocation activities, frequently seen in UFG metals. The deformation twin nucleation behavior will be discussed based on in-situ TEM deformation experiments and nanoscale strain distribution analyses results.

Twin Boundaries and Stacking Faults in Monazite (Monoclinic LaPO4)

2004 ◽  
Vol 819 ◽  
Author(s):  
Randall S. Hay
Keyword(s):  
Room Temperature ◽  
Deformation Twin ◽  
Stacking Faults ◽  
Temperature Deformation ◽  
Formation Mechanisms ◽  
Twin Boundaries ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Fault Migration ◽  
Lattice Formation

AbstractMonazite (LaPO4) was indented at room temperature. Deformation twin boundaries and stacking faults were characterized by high resolution transmission electron microscopy. Kinked deformation twins were also characterized and analyzed. Three types of stacking faults associated with climb-dissociated partial dislocations were observed. Two were found on twin boundaries, and a third in the lattice. Formation mechanisms are discussed. The superimposition of stacking faults along twin boundaries during deformation twinning and the glide of climb-dissociated partial dislocations allowed by stacking fault migration are discussed. The possible relationship between the formation mechanisms for these defects and the low- temperature recrystallization and self-annealing of defects in monazite is considered.

Crystallography of deformation twin boundaries in a B2 type Ti–Ni alloy

2006 ◽  
Vol 438-440 ◽  
pp. 495-499 ◽  
Author(s):  
M. Nishida ◽  
M. Matsuda ◽  
T. Fujimoto ◽  
K. Tanka ◽  
A. Kakisaka ◽  
...  
Keyword(s):  
Deformation Twin ◽  
Twin Boundaries ◽  
Ni Alloy

scholarly journals A correlation between grain boundary character and deformation twin nucleation mechanism in coarse-grained high-Mn austenitic steel

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chang-Yu Hung ◽  
Yu Bai ◽  
Tomotsugu Shimokawa ◽  
Nobuhiro Tsuji ◽  
Mitsuhiro Murayama
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Austenitic Steel ◽  
Deformation Twin ◽  
Local Stress ◽  
Nucleation Mechanism ◽  
Stacking Fault ◽  
Dislocation Dynamics ◽  
Coarse Grained ◽  
Twin Nucleation

AbstractIn polycrystalline materials, grain boundaries are known to be a critical microstructural component controlling material’s mechanical properties, and their characters such as misorientation and crystallographic boundary planes would also influence the dislocation dynamics. Nevertheless, many of generally used mechanistic models for deformation twin nucleation in fcc metal do not take considerable care of the role of grain boundary characters. Here, we experimentally reveal that deformation twin nucleation occurs at an annealing twin (Σ3{111}) boundary in a high-Mn austenitic steel when dislocation pile-up at Σ3{111} boundary produced a local stress exceeding the twining stress, while no obvious local stress concentration was required at relatively high-energy grain boundaries such as Σ21 or Σ31. A periodic contrast reversal associated with a sequential stacking faults emission from Σ3{111} boundary was observed by in-situ transmission electron microscopy (TEM) deformation experiments, proving the successive layer-by-layer stacking fault emission was the deformation twin nucleation mechanism, different from the previously reported observations in the high-Mn steels. Since this is also true for the observed high Σ-value boundaries in this study, our observation demonstrates the practical importance of taking grain boundary characters into account to understand the deformation twin nucleation mechanism besides well-known factors such as stacking fault energy and grain size.

Twin Boundaries and Stacking Faults in Monazite (Monoclinic LaPO4)

2004 ◽  
Vol 821 ◽  
Author(s):  
Randall S. Hay
Keyword(s):  
Room Temperature ◽  
Deformation Twin ◽  
Stacking Faults ◽  
Temperature Deformation ◽  
Formation Mechanisms ◽  
Twin Boundaries ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Fault Migration ◽  
Lattice Formation

AbstractMonazite (LaPO4) was indented at room temperature. Deformation twin boundaries and stacking faults were characterized by high resolution transmission electron microscopy. Kinked deformation twins were also characterized and analyzed. Three types of stacking faults associated with climb-dissociated partial dislocations were observed. Two were found on twin boundaries, and a third in the lattice. Formation mechanisms are discussed. The superimposition of stacking faults along twin boundaries during deformation twinning and the glide of climb-dissociated partial dislocations allowed by stacking fault migration are discussed. The possible relationship between the formation mechanisms for these defects and the low- temperature recrystallization and self-annealing of defects in monazite is considered.

Structural change of deformation twin boundaries in a heavily deformed γ-TiAl-based alloy

2000 ◽  
Vol 45 (6) ◽  
pp. 320-325 ◽  
Author(s):  
L.C Zhang ◽  
J.G Wang ◽  
G.L Chen ◽  
G Sauthoff
Keyword(s):  
Structural Change ◽  
Deformation Twin ◽  
Twin Boundaries
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