Work hardening of ultrafine-grained copper with nanoscale twins

Deformation twinning in nanocrystalline materials

“…Chen and Lu [305] measured the strain hardening rates of four UFG Cu samples -nt-Cu-20 with twin spacing of $20 ± 4 nm (nt = nanotwin), nt-Cu-36 with twin spacing of $36 ± 7 nm, nt-Cu-90 with twin spacing of 90 ± 26 nm, and UFG-Cu without twin, using uniaxial tensile tests. Fig.…”

“…52. The strain hardening rates of four copper samples measured by tensile tests: nano twinned sample with a twin spacing of 20 nm (nt-20 nm), nano twinned sample with a twin spacing of 36 nm (nt-36 nm), nano twinned sample with a twin spacing of 90 nm (nt-90 nm), and UFG sample without twin [305].…”

Size Effect and Deformation Mechanism in Twinned Copper Nanowires

“…Nanotwinned metallic materials, comprised of coherent twin boundaries (CTBs) with nanometerscale spacing, have been paid special attention since firstly reported by Lu et al [1] because of the unusual combination of ultra-high strength (on the order of 1 GPa for the nanotwinned Cu vs. 0.25 GPa for the coarse-grained Cu) and high tensile ductility (up to 14% for the nanotwinned Cu) [2][3][4], along with considerable work hardening [4][5][6]. Both experiments [7][8][9] and molecular dynamics (MD) simulations [2,[10][11][12][13] revealed that the novel mechanical properties of the nanotwinned metals originate from the size-dependent dislocation-CTB interactions.…”

Simulations of Mechanical Behavior of Polycrystalline Copper with Nano-Twins

“…All the parameters in Eq. (14) can be found in the experiment data of Shen et al And as shown in recent studies on the work hardening of ultrafine-grained copper with nanoscale twins [27] , Chen and Lu have indicated that the work hardening exponent N is decreased with the decreasing of twin lamellae thickness. So in the present numerical study, the work hardening exponents of different thickness twin lamellae are allowed to vary from 0.08 to 0.15.…”

“…When the exponent N is small, the occurrence of intergranular fracture will be deferred greatly but the effect of work hardening is not obvious. Recent studies on the work hardening of ultrafine-grained copper with nanoscale twins [27] have indicated that the conventional work hardening mechanism by the forest dislocations for the coarse grain FCC metal is not dominant due to the thin twin lamellae structures introduced. So the improvement of global ductility of NCT copper may benefit significantly from the decreasing work hardening exponent by a new work hardening mechanism in twin/matrix lamellae structures.…”