Abstract
Gradient-nanostructured material is an emerging category of material with spatial gradients in microstructural features. The incompatibility between gradient nanostructures (GNS) in the surface layer and coarse-grained (CG) core and their roles in extra strengthening and strain hardening have been well elucidated. Nevertheless, whether similar mechanisms exist within the GNS is not clear yet. Here, interactions between nanostructured layers constituting the GNS in a Ni alloy processed by surface mechanical rolling treatment were investigated by performing unique microtension tests on the whole GNS and three subdivided nanostructured layers at specific depths, respectively. The isolated nanograined layer at the topmost surface shows the highest strength but a brittle nature. With increasing depths, isolated layers exhibit lower strength but enhanced tensile plasticity. The GNS sample’s behavior complied more with the soft isolated layer at the inner side of GNS. Furthermore, an extra strain hardening was found in the GNS sample, leading to a greater uniform elongation (>3%) as compared to all of three constituent nanostructured layers. This extra strain hardening could be ascribed to the effects of the strain gradients arising from the incompatibility associated with the depth-dependent mechanical performance of various nanostructured layers.
Highlights
IntroductionGradient materials are a new category of material in which certain intrinsic microstructural characteristics and/or properties, such as grain/precipitate size, chemical composition, magnetism, are distributed in gradient along the depth [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]
A gradient nanostructures (GNS) was generated on the surface of a Ni alloy processed by surface mechanical rolling treatment (SMRT), and microtensile tests were performed on the whole GNS layer and three subdivided layers, respectively
A direct comparison on the mechanical response of various samples was made to reveal the extra strain hardening induced by the effects of the strain gradients within the GNS
Summary
Gradient materials are a new category of material in which certain intrinsic microstructural characteristics and/or properties, such as grain/precipitate size, chemical composition, magnetism, are distributed in gradient along the depth [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]. Gradient metals have exhibited great potentials for broad engineering applications due to enhanced properties of high strength, considerable ductility, and fatigue resistance, as compared to their homogeneous coarse-grained (CG) counterparts [5,6,7,16,17,18,19]. The microstructural gradients are readily achieved and tailored, and have attracted broad attention over the past decade [5]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
