Super-strengthening and stabilizing with carbon nanotube harnessed high density nanotwins in metals by shock loading

Abstract

CNTs reinforced metal composites has great potential due to their superior properties, such as light weight, high strength, low thermal expansion and high thermal conductivity. The current strengthening mechanisms of CNT/metal composite mainly rely on CNTs’ interaction with dislocations and CNT’s intrinsic high strength. Here we demonstrated that laser shock loading the CNT/metal composite results in high density nanotwins, stacking fault, dislocation around the CNT/metal interface. The composites exhibit enhanced strength with excellent stability. The results are interpreted by both molecular dynamics simulation and experiments. It is found the shock wave interaction with CNTs induces a stress field, much higher than the applied shock pressure, surrounding the CNT/metal interface. As a result, nanotwins were nucleated under a shock pressure much lower than the critical values to generate twins in metals. This hybrid unique nanostructure not only enhances the strength, but also stabilize the strength, as the nanotwin boundaries around the CNTs help pin the dislocation movement.

Warm laser shock peening without coating induced phase transformations and pinning effect on fatigue life of low-alloy steel

“…The laser ablation, which produces intense plasma shock waves generates deep compressive RS. This compressive RS induced deformation mechanism is solely a cold working process which improves the fatigue, wear and corrosion properties of metallic materials [5,[9][10][11].…”

Effects of twin orientation and spacing on the mechanical properties of Cu nanowires

“…Experimental studies and molecular dynamics (MD) simulations have confirmed that nanomaterials containing nanoscale twins exhibit ultrahigh strength 1 – 4 or even beyond the elastic limit 5 , significant strain hardening effects 6 and crack resistance 7 . Based on the strengthening mechanism, the introduction of coherent twin boundaries (CTBs) has become a well-known means to strengthen nanocrystalline materials 8 – 11 . Previous researches mainly focused on the effects of TB spacing 6 , 12 , 13 and cross-section shape 14 on the mechanical properties of twinned NWs with the CTBs perpendicular to the NW axis.…”

Balancing biofunctional and biomechanical properties using porous titanium reinforced by carbon nanotubes

“…Many studies have described the twining effect and analyzed the relationship with grain morphology and size. For example, Reinhold et al 46 evaluated the twining in magnetic shape memory alloys (Ni-Mn-Ga) observing a preferential localization in planar and sharp ridges and valleys which are similar to the 47 reported the development of nanotwins in composites based on Ti and CNT observing similar twin effect as Ti-5% and 10% CNT substrates. Besides the potential improvements in hardness and strength due to twining, the presence of CNT it is expected to increase the mechanical strength of the blend because the CNT can reduce the stress concentration caused by the material porosity.…”

“…For example, Reinhold et al evaluated the twining in magnetic shape memory alloys (Ni–Mn–Ga) observing a preferential localization in planar and sharp ridges and valleys which are similar to the morphology of Ti grain boundaries. In another study, Li et al reported the development of nanotwins in composites based on Ti and CNT observing similar twin effect as Ti‐5% and 10% CNT substrates.…”