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instability induced by incoherent twin boundary in nanotwinned copper

1. Strain hardening and softening in nanotwinned Cu:

Nanotwinned Cu foils with about 99% coherent twin boundaries (TBs) among all the boundaries were made. These coherent

TBs, with an average spacing of 25 nm, were engineered approximately parallel to foil surfaces. Low plane-strain deformation

enhances the hardness by refining microstructure and introducing dislocations. High plane-strain deformation results in crystallographic

lattice rotation and reaction between dislocations and coherent TBs, and induces incoherent TBs, thus twin coarsening and

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what's detwinning

Now I am doing some work about nanotwinned copper, and don't understand what's the nature of "detwinning". 

Could any disappearance of the original nanotwin structure and the formation of a single grain or a new twin structure with TBs in a different orientation and/or with different TB spacing be called detwinning?

Thickness dependent critical strain in Cu films adherent to polymer substrate

For the polymer-supported metal thin films that are finding increasing applications, the critical strain to nucleate microcracks ( εc ) should be more meaningful than the generally measured rupture strain. In this paper, we develop both electrical resistance method and microcrack analyzing method to determine εc of polymer-supported Cu films simply but precisely. Significant thickness dependence has been clearly revealed for εc of the polymer-supported Cu films, i.e., thinner is the film lower is εc . This dependence is suggested to cause by the constraint effect of refining grain size on the dislocation movability.

rupture of Cu films

Dear Prof. Li, i have made two figures about rupture strains of  films on elastomer according to the datas shown in your papers-- "Deformability of thin metal films on elastomer substrates" International Journal of Solids and Structures 43 (2006) 2351–2363. and "Stretchability of thin metal films on elastomer substrates" APL85(2004). According to the papers, the stiffer or thicker the elastomer substrates, the larger rupture strains, then where would be the curve with H/h =200? Whether the rupture strain is even large, according to your simulations?

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