Cu–Nb Nanocomposite Wires Processed by Severe Plastic Deformation: Effects of the Multi‐Scale Microstructure and Internal Stresses on Elastic‐Plastic Properties

Abstract

Several recent studies have shed light on the effect of microstructure architecture onto the macroscopic mechanical properties of materials and the possibility to use a new degree of freedom in the tailoring of multi-functional properties of structure materials: the ordering of microstructure at the mesoscale. [1,2] If this concept is extensively present in natural materials such as wood or shells, where multi-modal or multi-scale architecture can be found, it is rather recently that it is consciously applied to design modern engineering materials. [1] For example, this is the case in the steel industry where complex multi-phased microstructures are produced to provide multi-functionality such as high elastic limit for prolonged lifetime and ductility for improved formability. Similarly, nanocomposite metals are seen as strong candidates for several applications in extreme environment (high dose irradiation, severe deformation, shock, high magnetic field, high temperature, etc.) because the combination of refined microstructure, inter-phase boundaries and hierarchy provides unique macroscopic properties, not available in standard materials. [3] However, the main challenge still remains in the full understanding of the complex interaction existing between materials properties and their architecture, in particular when size effects affect the elementary physical mechanisms. In this field, combined experimental and simulation efforts are mandatory.From the experimental point of view, the full knowledge of the microstructure is necessary, from atomic to macroscopic scales; this can be obtained by a combination of standard and advanced characterization techniques. Similarly, to characterize the impact of architecture on macroscopic mechanical properties, specific testing techniques must be developed: in this field, the combination of deformation and diffraction appears to be particularly well suited. Thanks to the high penetration depth of thermal neutrons or high energy X-rays (at synchrotrons) and the crystallographic selectivity of diffraction, in-situ deformation tests under neutrons or X-rays can indeed bring deep insight into the role of internal stresses and reveal the phase-specific deformation behavior and strengthening mechanisms of complex materials. In the present article, the results obtained in the case of Cu-Nb COMMUNICATION[*] Dr.

Multiscale modeling of the elastic behavior of architectured and nanostructured Cu–Nb composite wires

“…The microstructural state of Cu-Nb wires has been studied by Scanning Electron Microscope, Scanning Transmission Electron Microscope and Xray diffraction by (Vidal et al, 2007;Thilly et al, 2009;Dubois et al, 2010;Dubois, 2010;Dubois et al, 2012). In the present work, we define as the average grain length along the longitudinal wire axis x 1 and d as the average grain diameter in the transverse x 2 -x 3 cross-section.…”

“…x 2 Figure 1: Successive section views of the Cu/Nb/Cu nano-composite wires (Dubois, 2010;Dubois et al, 2012). In recent years, there has been an increasing demand for next-generation structural nano-materials that exhibit extraordinarily high strength, electrical conductivity, hardness, ductility, thermal stability and radiation damage tolerance.…”

“…In this field, combining material characterization and multi-scale modeling is mandatory. The previous studies on the Cu-Nb nano-composite wires and laminates deal with deformation mechanisms (Thilly et al, 2001), hardness (Thilly et al, 2002a), Cu-Nb interfaces (Beyerlein et al, 2014;Carpenter et al, 2015), Ultimate Tensile Strength (Vidal et al, 2007), plastic flow stability (Misra and Hoagland, 2007), Bauschinger effect (Thilly et al, 2007;Zhang et al, 2013;Badinier et al, 2014), yield criterion (Thilly et al, 2009), texture evolution (Lim and Rollett, 2009;Lee et al, 2012;Hansen et al, 2013), thermal stability and internal stresses (Dubois et al, 2010(Dubois et al, , 2012, and electrical conductivity (Thilly, 2000;Dubois, 2010;Gu et al, 2015).…”

Modélisation multi-échelle du comportement électrique de nano-composites Cu-Nb

“…Comme dans Hervé et Zaoui [18], sur la figure 2, la phase i se situe dans la couronne limitée par les deux cylindres concentriques de rayon [6,7]. Fig.…”

Local strain matching between Nb nanowires and a phase transforming NiTi matrix in an in-situ composite

“…Whereas achieving good improvements in mechanical properties, these composites have not yet delivered what may be expected of the exceptional properties of the nanowires based on the law of mixture. The main reason is that the embedded nanowires are normally found to exhibit maximum elastic strains much lower than their capabilities in free standing state [9,10]. This obstacle has defied all the efforts to create high-performance metallic composites using nanowires.…”