The plasticity of highly oriented nano-layered Zr/Nb composites

Abstract

In prior work, bulk lamellar composites of pure zirconium and niobium (Zr/Nb) were manufactured by accumulative roll bonding (ARB). After the substantial amounts of straining required to refine the layers to nanoscale dimensions, formation of highly oriented Zr crystals was observed. In this work, we employ a spatially resolved multiscale crystal plasticity based model in 3D to study the orientational stability of Zr single crystals and Zr/Nb bicrystals during rolling deformation. The analysis reveals that predominant texture components arise due to substantially reduced ratios of slip resistances among the prismatic, pyramidal I <c+a>, and basal slip systems. In support, density functional theory (DFT) calculations of generalized stacking fault energy curves on these three slip systems suggest that the ratio of critical stresses to form these dislocations are within 2.5 times. This finding of reduced anisotropy in Zr at the nanoscale can provide insight into the design of nano-structuring processes for target textures, such as those containing highly oriented grains.

Heterostructured materials: superior properties from hetero-zone interaction

“…In spite of these limitations, ARB has been employed to manufacture nanolaminate sheets of Ag/Fe, Ag/Ni, Cu/Nb, Cu/Ta, Zr/Nb, as well as ultrafine laminate sheets of Mg-alloy/Nb [41,[141][142][143][144][145] (see Figure 5(d)). Less intuitively, ARB has proven capable of producing low-energy, atomically ordered bi-phase interfaces in Zr/Nb and Cu/Nb systems [32,146]. For the Cu/Nb system, the sheet material exhibited similar strengths and even better radiation resistance and thermal stability than the deposited foils [45,135] (see Figure 5(c)).…”

Room temperature deformation mechanisms of Mg/Nb nanolayered composites

“…The CP-based formulation used in CPFE is given in many prior studies. 73,[75][76][77] Below special treatment of elastic and plastic behavior is extended to reflect the BCC or HCP crystal structure of Mg and also to treat the interface-affected resistance to dislocation glide characteristic of motion within confined nanoscale layers. Since our interest lies in the active deformation mechanisms during plastic deformation, we made a reasonable guess for the elastic response of this nanolayered composite.…”

“…From these curves, the ISS can be calculated. 63,73,74 Table III shows the corresponding ISS values for each slip mode and for interface shearing in three in-plane directions of the BCC-NbkBCC-Mg interface and the BCC-NbkHCP-Mg interface. The values for ISS resisting interfacial shearing are much higher than those for slip, suggesting that slip would be the preferred mode of deformation of these nanolaminates.…”

Solubility in Zr-Nb alloys from first-principles

“…Being biocompatible, they can also be employed in biomedical applications such as knee and hip replacement for orthopedic surgeries [6], and their potential low magnetic susceptibility make them attractive for implants compatible with magnetic resonance imaging [7,8]. In addition, Zr-Nb multilayers have been investigated due to their superconducting properties [9,10], or, more recently, for their possible superior mechanical performance and irradiation resistance [11][12][13][14][15][16].…”