Computer simulation of strength and ductility of nanotwin-strengthened coarse-grained metals

Abstract

The superior strength-ductility combination in nanotwin (NT)-strengthened metals has provided a new potential for optimizing the mechanical properties of coarse-grained (CG) metals. In this paper computer simulations based on the mechanism-based strain gradient plasticity and the Johnson–Cook failure criterion have been carried out to uncover the critical factors that serve to provide this dual function. Our results indicate that both the distribution characteristics of the NT regions and the constitutive relations of the NT phase can have a significant impact on the strength and ductility of the CG Cu strengthened by the NT regions. In particular, twin spacing, distribution characteristics such as arrangement, shape and orientation, together with volume fraction of the NT regions, can all have significant effects. Along the way, we also discovered that microcrack initiation, coalescence and deflection constituted the entire failure process. Significant insights into the morphology of NT regions that could deliver superior strength and ductility combination for CG metals have been established.

Nanotwinned and hierarchical nanotwinned metals: a review of experimental, computational and theoretical efforts

“…25,51,53 Corresponding to these experimental outcomes, a large quantity of theoretical studies are available, such as the intrinsic size effects and plastic anisotropy, the stability of NT structures, 54,55 the effect of surface stress 56,57 and NT structures in CG system on the mechanical properties of metals. [58][59][60][61] Moreover, the electrical conductivity of NT bulk metals is similar to the conventional CG counterpart but much higher than NC metals. 22 NT structures lead to a significant variation of the electronic and optical properties of nanowires.…”

Recent Progress on Regulating Strategies for the Strengthening and Toughening of High-Strength Aluminum Alloys

“…In addition to the above studies, the design of alloy composition and microalloying can be carried out for the purpose of reducing defects existing in the manufacturing process by adjusting the alloying elements, including Hume-Rothery rules [72] considering electronegativity, relative valence electrons, and other factors, as well as a design method for a "cluster and connected atom" structure model based on local atomic clusters [73] In addition to the above studies, the design of alloy composition and microalloying can be carried out for the purpose of reducing defects existing in the manufacturing process by adjusting the alloying elements, including Hume-Rothery rules [72] considering electronegativity, relative valence electrons, and other factors, as well as a design method for a "cluster and connected atom" structure model based on local atomic clusters [73]. B.…”

The direct and indirect effects of nanotwin volume fraction on the strength and ductility of coarse-grained metals

“…Our approach here is numerical. In a recent numerical study we have discovered that twin spacing and distribution characteristics of NT regions have significant effects on the strength and ductility of the CG Cu strengthened by NT regions [45].…”

“…However, the main results we reported were obtained only for a fixed volume fraction of NT regions at ~20%. As a consequence the effects of NT regions over the broad range of volume fraction have not been investigated [45]. As the volume fraction changes, the effects of twin spacing and microstructure on the overall strength and ductility are also likely to change -indirect effects of volume fraction of NT regions may arise from the twin spacing and microstructure.…”

“…The fitting results, constitutive parameters of each phase in the CG Cu strengthened by NT regions, are tabulated in Ref [45][55] is employed to express the damage parameter…”