Grain size effect on deformation twinning propensity in ultrafine-grained hexagonal close-packed titanium

The grain size effect on blunting of cracks in nanocrystalline and ultrafine-grained materials (UFG) is theoretically described. Within our description, lattice dislocations emitted from cracks are stopped at grain boundaries. The stress fields of these dislocations suppress further dislocation emission from cracks in nanocrystalline and UFG materials, and the suppression depends on grain size. The dependences of the number of dislocations emitted by a crack on grain size (ranging from 10 to 300 nm) in Cu and 3C-SiC (the cubic phase of silicon carbide) are calculated which characterize the grain size effect on crack blunting that crucially influences ductility of these materials.

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Grain Size Effect on Deformation Twinning and De-Twinning in a Nanocrystalline Ni-Fe Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.667-669.181 ◽

2010 ◽

Vol 667-669 ◽

pp. 181-186 ◽

Cited By ~ 2

Author(s):

Song Ni ◽

Yan Bo Wang ◽

Xiao Zhou Liao ◽

Saleh N. Alhajeri ◽

H.Q. Li ◽

...

Keyword(s):

Grain Size ◽

Size Effect ◽

High Pressure Torsion ◽

Deformation Twinning ◽

Grain Size Effect ◽

Grain Sizes ◽

Transmission Electron ◽

Average Grain Size ◽

Study Results ◽

Electrochemically Deposited

The effect of grain size on the deformation twinning and de-twinning in a nanocrystalline Ni-Fe alloy was investigated using transmission electron microscopy. Specimens with different grain sizes were obtained by severely deforming an electrochemically deposited nanocrystalline Ni-20wt.% Fe alloy using high-pressure torsion, which resulted in continuous grain growth from an average grain size of ~ 21 nm in the as-deposited material to ~ 72 nm for the highest strain applied in this study. Results show that deformation de-twinning occurs at very small grain sizes while deformation twinning takes place when the grain size is larger than ~ 45 nm. The mechanism of the observed grain size effect on twinning and de-twinning is briefly discussed.

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Investigation on Grain Size Effect of Rolling Texture in Copper

Materials Science Forum ◽

10.4028/www.scientific.net/msf.850.857 ◽

2016 ◽

Vol 850 ◽

pp. 857-863 ◽

Cited By ~ 2

Author(s):

Yao Jiang ◽

Jing Tao Wang ◽

Yue Wang ◽

Jian Yin

Keyword(s):

Grain Size ◽

Cold Rolling ◽

Size Effect ◽

Rolling Texture ◽

Coarse Grained ◽

Grain Size Effect ◽

Shear Texture ◽

Ecap Pass ◽

Ultrafine Grained ◽

Pole Figures

Cold rolling (CR) was conducted on coarse grained (CG) and ultrafine-grained (UFG) coppers, obtained by 1 and 8 passes in the equal channel angel pressing (ECAP), to investigate the effect of grain size on rolling texture. The microstructure was refined to UFG (~420 nm) with the ECAP pass increased to 8, while only band-like CG microstructure was observed in the 1 pass processed copper. The influence of the texture before CR could be excluded as the crystallographic texture kept similar for different ECAP pass. Pole figures (PFs) showed that the shear texture introduced by ECAP was replaced by rolling texture after CR. Furthermore, the rolling texture was a kind of classical copper-type for the CG copper, while a brass-type rolling texture was observed in the UFG copper. TEM results confirmed that the deformation nanotwins were only observed in the UFG copper, while the microstructure of CG copper was further compressed and subdivided. It indicated that the observed differences in rolling texture component and density might be contributed to the grain size effect which resulted in different deformation mechanism and grain subdivision behavior.

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