Serrated Behaviors and Plasticity of Nb-Alloyed Cu-Based Bulk Metallic Glasses
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Serrated Behaviors and Plasticity of Nb‑Alloyed Cu‑Based Bulk Metallic Glasses Jili Wu1 · Ziyi Zhou1 · Zhen Peng1 Received: 12 February 2019 / Accepted: 28 July 2019 © The Korean Institute of Metals and Materials 2019
Abstract This paper is to disclose the plastic deformation mechanism of 3 Nb-alloyed bulk metallic glasses and composites via the analysis of serration dynamics. The as-cast alloys with 1.0 at% and 2.0 at% of Nb element display the large time window of serrated events, implying that the serrated behavior can dynamically retain in a long-time scale and thus the alloys are endowed the largest compressive plasticity. The statistic results suggest that the serrated flow of both alloys with 1.0 at% and 2.0 at% Nb element achieves the self-organized critical state. The normal probability plots were utilized to further evaluate serrated dynamics and demonstrate that large deviations from the mean value of stress drops facilitate the self-organized critical state of serrations. This work suggests that large plastic bulk metallic glasses and composites are characterized by non-normal probability of serration statistics during plastic deformation. Keywords Serrated behaviors · Plasticity · Bulk metallic glass · Serration dynamics
1 Introduction The understanding of plastic deformation of bulk metallic glasses (BMGs) has been devoted much efforts via investigating a variety of deformation behaviors under numerous and different circumstances, such as construction of composite structure [1–3], dynamic loading [4] and microscopic observation [5, 6] etc. Plastic strain of BMGs is usually endured with localized narrow shear banding which is a main cause for the catastrophic failure during the deformation [7]. Interestingly, the constraint and multiplication of shear bands is a favorable approach for improving the plasticity of deformed BMGs [8, 9]. On several BMGs with remarkable plasticity, shear bands are monitored in the forms of discrete bursts or serrated flow in which stress dramatically drops and then increases immediately during the
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12540-019-00405-0) contains supplementary material, which is available to authorized users. * Zhen Peng [email protected] 1
School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, People’s Republic of China
plastic deformation, such as stress–strain curves of uniaxial deformation or load–displacement curves of indentation [9]. The serrated flow in BMGs is associated to the constraint and blocking during the movement of shear bands which usually is response of plastic deformation. Theoretically, shear banding is generally accompanied with shear softening which is a main reason for fracture within a little plastic strain of BMGs [10–12]. Generally, serrated flow and shear banding are strongly dependent with composition [13], aspect ratio [14, 15], deformation degree [16, 17], strain rate [11, 18, 19] and temperature [20, 21] etc. The aspect ratio has
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