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Qingchuan Zhang - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of a portevin Le Chatelier band in ni co based superalloys in relation to γʹ precipitates at 500
Journal of Materials Science & Technology, 2020Co-Authors: Yanke Liu, Guoming Han, Chenggang Tian, Chuanyong Cui, Yulong Cai, Guoliang Zhang, Qingchuan ZhangAbstract:Abstract The macroscopically localized deformation behaviors of Ni–Co-based superalloys with different γ′ precipitate content were investigated at 500 °C and 1 × 10−4 s−1 via an in situ method namely, digital image correlation (DIC). The DIC results showed that the serrated flow of the stress–strain curves was accompanied by localized deformation of the specimens. The fracture morphology was characterized mainly by transgranular fracture with numerous dimpLes in the low γ′ content alloy, and intergranular fracture with large fracture section in the high γ′ content alloy. The Portevin–Le Chatelier (PLC) effect occurred in the investigated Ni–Co-based superalloys. Furthermore, the localized deformation of the high γ′ content alloy was more severe than that of the low γ′ content alloy, and the band width was slightly larger. Moreover, for the first-time ever, a special propagation feature, namely ±60° zigzag bands characterized by head-to-tail connections, was observed in the high γ′ content alloy.
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investigation of portevin Le Chatelier band strain and elastic shrinkage in al based alloys associated with mg contents
Journal of Materials Science & Technology, 2017Co-Authors: Yulong Cai, Di Zhang, Suli Yang, Qingchuan ZhangAbstract:The Portevin–Le Chatelier (PLC) effect in Al–2.30wt%Mg, Al–4.57wt%Mg and Al–6.91wt%Mg alloys has been investigated at various applied strain rates at room temperature in this study. Three-dimensional digital image correlation (3D-DIC) technique was applied to obtaining the further insight into the spatiotemporal characteristics, in particular the influence of Mg content on deformation behaviors. Mg content has a pronounced effect on serration characteristics, including the serration type and amplitude; Mg content tends to weaken the spatial correlation of the propagative bands. Additionally, the serration amplitude linearly increases with the maximum PLC band strain; high Mg content generates a higher PLC band strain at a given serration amplitude compared with low Mg content. Mg content is found to be effective to enhance the serration amplitude, the maximum PLC band strain and also the amount of elastic shrinkage outside PLC bands.
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influence of γʹ precipitates on portevin Le Chatelier effect of ni based superalloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Guoming Han, Chenggang Tian, Chuanyong Cui, Yulong Cai, Qingchuan ZhangAbstract:Abstract The γ′ precipitate plays a critical roLe in improving the mechanical properties of Ni-based superalloys. An undesirabLe phenomenon referred to as the Portevin–Le Chatelier (PLC) effect always appears in Ni-based superalloys deformed within specific ranges of strain rate and temperature. In order to systematically investigate the influence of the γ′ precipitates on the PLC effect, four Ni-based superalloys with various γ′ contents were designed and fabricated. Microscopic observations from transmission eLectron microscopy (TEM) indicated that the volume fraction of the γ′ phase was consistent with the designed value. Furthermore, analysis of energy dispersive spectroscopy (EDS) results reveaLed that the γ matrix of all the alloys consisted of the same components. Uniaxial tensiLe tests were performed at strain rates and temperatures ranging from 1×10 − 4 to 3×10 −3 s −1 and 300–500 °C, respectively. We found that the ultimate strength increased whiLe the elongation decreased with increasing γ′ content. In addition, the serration changed from type A to type B and to type C with increasing temperature, decreasing strain rate or increasing γ′ content; the amplitude of type B serrations was described by unimodal or bimodal distributions. Increasing volume fraction of γ′ precipitates shifted the region in which the PLC effect occurred, to the range of low temperatures and high strain rates. Moreover, the serration amplitude increased with increasing γ′ content at a given temperature, which indicated that the γ′ precipitate increases the dynamic strain ageing (DSA) effect.
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investigation of portevin Le Chatelier effect in 5456 al based alloy using digital image correlation
Optics and Lasers in Engineering, 2015Co-Authors: Teng Cheng, Yulong Cai, Yue Gao, Yong Zhang, Qingchuan ZhangAbstract:Abstract A variety of experimental methods have been proposed for Portevin-Le Chatelier (PLC) effect. They mainly focused on the in-plane deformation. In order to achieve the high-accuracy measurement, three-dimensional digital image correlation (3D-DIC) was employed in this work to investigate the PLC effect in 5456 Al-based alloy. The temporal and spatial evolutions of deformation in the full field of specimen surface were observed. The large deformation of localized necking was determined experimentally. The distributions of out-of-plane displacement over the loading procedure were also obtained. Furthermore, a comparison of measurement accuracy between two-dimensional digital image correlation (2D-DIC) and 3D-DIC was also performed. Due to the theoretical restriction, the measurement accuracy of 2D-DIC decreases with the increase of deformation. A maximum discrepancy of about 20% with 3D-DIC was observed in this work. Therefore, 3D-DIC is actually more essential for the high-accuracy investigation of PLC effect.
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three types of portevin Le Chatelier effects experiment and modelling
Acta Materialia, 2007Co-Authors: Huifeng Jiang, Qingchuan Zhang, Zhenyu Jiang, Zhongjia Chen, Xuedong Chen, Jinghong FanAbstract:Abstract By employing the dynamic digital speckLe pattern interferometry (DSPI) technique, three types of Portevin–Le Chatelier (PLC) effects are investigated systematically, with emphasis on the temporal and spatial dynamic features. A new model based on the dynamic strain aging (DSA) mechanism is proposed, and three types of PLC effects at different applied strain rates are reproduced by it when the spatial coupling is included. The dynamic interaction between dislocation and diffusing solutes is also studied through the developed constitutive model. The results self-consistently exhibit three branches of the dislocation–solute interaction, two stabLe branches at low and high strain rate (or dislocation velocity), which correspond to the effective aging or unpinning of dislocation, respectively, and a metastabLe one at the intermediate strain rate, where negative strain rate sensitivities result from the dynamic strain aging.
M A Lebyodkin - One of the best experts on this subject based on the ideXlab platform.
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Kinematics of formation and cessation of type B deformation bands during the Portevin-Le Chatelier effect in an AlMg alloy
Results in Physics, 2019Co-Authors: M A Lebyodkin, D. A. Zhemchuzhnikova, T A Lebedkina, E C AifantisAbstract:Using digital image correlation technique, various stages of development of localized deformation bands caused by the Portevin-Le Chatelier (PLC) instability of plastic flow are examined at strain rates corresponding to abrupt stress drops akin to relaxation oscillations. Diffuse deformation bands are found prior to stress drops. Although the respective increase in the local strain rate is relatively weak, it is immediately observed over the entire region of the nascent PLC band. Moreover, diffuse bands are also detected at the beginning of reloading after the end of stress drops, thereby indicating that the termination of plastic instability proceeds through a progressive depLetion of the strain localization. Weak transient strain localizations that do not develop into a PLC band are also observed during reloading.
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interrelation between the portevin Le Chatelier effect and necking in almg alloys
International Journal of Plasticity, 2018Co-Authors: D. A. Zhemchuzhnikova, Tatiana Lebedkina, M A Lebyodkin, Diana Yuzbekova, Anna Mogucheva, Rustam KaibyshevAbstract:Abstract Plastic flow instability caused by the Portevin Le-Chatelier (PLC) effect and its influence on the necking instability were studied in a binary and a precipitation-strengthened AlMg alloy using the digital image correlation (DIC) technique. Coarse-grained structure and two different fine-grained states distinctly distinguished by dislocation density were produced in both alloys using similar routes of thermomechanical processing. The patterns of stress serrations and strain localization observed at different strain rates include virtually all common types of behavior of the PLC effect. Besides, particular spatiotemporal patterns testifying to a concurrency between the propagation and localization of deformation bands are detected at low strain rates. Despite this diversity, the analysis of deformation curves with smoothened-out serrations bears evidence that the onset of necking always corresponds to the geometric Considere condition. NevertheLess, visualization of the evolution of the local strain-rate field using DIC indicates that the two mechanisms of plastic instability are closely interrelated and modify each other's behavior. The neck formation is associated with a progressive immobilization of the PLC bands, ending by the ultimate strain localization. The coexistence of two kinds of instability during necking gives rise to specific spatiotemporal patterns including oscillatory strain localization.
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effect of microstructure on continuous propagation of the portevin Le Chatelier deformation bands
International Journal of Plasticity, 2017Co-Authors: Diana Yuzbekova, D. A. Zhemchuzhnikova, Tatiana Lebedkina, M A Lebyodkin, Anna Mogucheva, Rustam KaibyshevAbstract:Abstract Influence of severe plastic deformation (SPD) on plastic instability associated with the Portevin-Le Chatelier (PLC) effect was investigated in an AlMg alloy in a high strain-rate range corresponding to the well-known phenomenon of continuous propagation of PLC bands. Comparison with the model coarse-grained alloy reveals numerous unusual features of spatiotemporal behavior observed after different kinds of SPD processing that gives rise to an extreme grain refinement and an increase in the lattice dislocation density. Whereas SPD strongly alters the deformation curves, Leading to either suppression of stress serrations or occurrence of serration types usually associated with static deformation bands, the band propagation persists in all material states. Surprisingly, smooth plastic deformation of the mostly work-hardened alloy neither corresponds to a uniform plastic flow but is related to propagation of a deformation band. The effect of the microstructure parameters on jerky flow can be explained through their influence on the propagation velocity and degree of localization of plastic deformation in the PLC bands. In particular, the loss of the PLC band mobility is discussed in relation with the conditions for the onset of necking and the formation of the localized shear band Leading to fracture.
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geometrically non linear modeling of the portevin Le Chatelier effect
Computational Materials Science, 2009Co-Authors: Thomas Bohlke, Yuri Estrin, G Bondar, M A LebyodkinAbstract:Abstract In this work we investigate the plastic instabilities associated with the Portevin–Le Chatelier (PLC) effect in Al alloy 2024. A semi-phenomenological approach is taken. A simpLe geometrically non-linear elastic–viscoplastic constitutive model is proposed for simulation of material response under various applied strain rates. Using the model we determine numerically the relation between the critical strain for the onset of discontinuous yielding and the applied strain rate. The results obtained are in very good quantitative agreement with the availabLe experimental data (colLected from tests at room temperature) and cover both the normal and the inverse behavior of the critical strain. The simulations are performed using non-linear finite eLement method. Additional verification of the proposed constitutive framework was carried out using statistical analysis of the simulated stress–time series. A transition from a non-linear chaotic regime to self-organized critical behavior of the localized strain bands were predicted in terms of the temporal two-point correlation function of the stress–time series. Finally we investigated the influence of different factors, such as the geometry of the specimen, its orientation with respect to the rolling direction and loading conditions (strain rate), on the type of PLC instabilities and the critical conditions for their onset.
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effect of deformation geometry on the intermittent plastic flow associated with the portevin Le Chatelier effect
Acta Materialia, 2008Co-Authors: T A Lebedkina, M A LebyodkinAbstract:Abstract The unstabLe plastic flow caused by the Portevin–Le Chatelier effect is studied experimentally. Non-local effects due to strain heterogeneity are addressed by comparing the statistical and multifractal properties of tension and compression deformation curves of an AlMg alloy. Power-law statistical distributions and multifractal scaling are found in certain experimental conditions, and provide a quantitative characterization of the plastic-flow intermittency. The analysis reveals distinct temporal patterns associated with stress serrations in tension and compression, refLecting distinct modes of the colLective dislocation dynamics. In contrast, the onset of instability follows similar relationships in both loading conditions. This similarity justifies the conventional approach to modeling the loss of stability of a uniform plastic flow as a local property, governed by the homogenized behavior of the dislocation ensembLe.
Yulong Cai - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of a portevin Le Chatelier band in ni co based superalloys in relation to γʹ precipitates at 500
Journal of Materials Science & Technology, 2020Co-Authors: Yanke Liu, Guoming Han, Chenggang Tian, Chuanyong Cui, Yulong Cai, Guoliang Zhang, Qingchuan ZhangAbstract:Abstract The macroscopically localized deformation behaviors of Ni–Co-based superalloys with different γ′ precipitate content were investigated at 500 °C and 1 × 10−4 s−1 via an in situ method namely, digital image correlation (DIC). The DIC results showed that the serrated flow of the stress–strain curves was accompanied by localized deformation of the specimens. The fracture morphology was characterized mainly by transgranular fracture with numerous dimpLes in the low γ′ content alloy, and intergranular fracture with large fracture section in the high γ′ content alloy. The Portevin–Le Chatelier (PLC) effect occurred in the investigated Ni–Co-based superalloys. Furthermore, the localized deformation of the high γ′ content alloy was more severe than that of the low γ′ content alloy, and the band width was slightly larger. Moreover, for the first-time ever, a special propagation feature, namely ±60° zigzag bands characterized by head-to-tail connections, was observed in the high γ′ content alloy.
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investigation of portevin Le Chatelier band strain and elastic shrinkage in al based alloys associated with mg contents
Journal of Materials Science & Technology, 2017Co-Authors: Yulong Cai, Di Zhang, Suli Yang, Qingchuan ZhangAbstract:The Portevin–Le Chatelier (PLC) effect in Al–2.30wt%Mg, Al–4.57wt%Mg and Al–6.91wt%Mg alloys has been investigated at various applied strain rates at room temperature in this study. Three-dimensional digital image correlation (3D-DIC) technique was applied to obtaining the further insight into the spatiotemporal characteristics, in particular the influence of Mg content on deformation behaviors. Mg content has a pronounced effect on serration characteristics, including the serration type and amplitude; Mg content tends to weaken the spatial correlation of the propagative bands. Additionally, the serration amplitude linearly increases with the maximum PLC band strain; high Mg content generates a higher PLC band strain at a given serration amplitude compared with low Mg content. Mg content is found to be effective to enhance the serration amplitude, the maximum PLC band strain and also the amount of elastic shrinkage outside PLC bands.
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influence of γʹ precipitates on portevin Le Chatelier effect of ni based superalloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Guoming Han, Chenggang Tian, Chuanyong Cui, Yulong Cai, Qingchuan ZhangAbstract:Abstract The γ′ precipitate plays a critical roLe in improving the mechanical properties of Ni-based superalloys. An undesirabLe phenomenon referred to as the Portevin–Le Chatelier (PLC) effect always appears in Ni-based superalloys deformed within specific ranges of strain rate and temperature. In order to systematically investigate the influence of the γ′ precipitates on the PLC effect, four Ni-based superalloys with various γ′ contents were designed and fabricated. Microscopic observations from transmission eLectron microscopy (TEM) indicated that the volume fraction of the γ′ phase was consistent with the designed value. Furthermore, analysis of energy dispersive spectroscopy (EDS) results reveaLed that the γ matrix of all the alloys consisted of the same components. Uniaxial tensiLe tests were performed at strain rates and temperatures ranging from 1×10 − 4 to 3×10 −3 s −1 and 300–500 °C, respectively. We found that the ultimate strength increased whiLe the elongation decreased with increasing γ′ content. In addition, the serration changed from type A to type B and to type C with increasing temperature, decreasing strain rate or increasing γ′ content; the amplitude of type B serrations was described by unimodal or bimodal distributions. Increasing volume fraction of γ′ precipitates shifted the region in which the PLC effect occurred, to the range of low temperatures and high strain rates. Moreover, the serration amplitude increased with increasing γ′ content at a given temperature, which indicated that the γ′ precipitate increases the dynamic strain ageing (DSA) effect.
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investigation of portevin Le Chatelier effect in 5456 al based alloy using digital image correlation
Optics and Lasers in Engineering, 2015Co-Authors: Teng Cheng, Yulong Cai, Yue Gao, Yong Zhang, Qingchuan ZhangAbstract:Abstract A variety of experimental methods have been proposed for Portevin-Le Chatelier (PLC) effect. They mainly focused on the in-plane deformation. In order to achieve the high-accuracy measurement, three-dimensional digital image correlation (3D-DIC) was employed in this work to investigate the PLC effect in 5456 Al-based alloy. The temporal and spatial evolutions of deformation in the full field of specimen surface were observed. The large deformation of localized necking was determined experimentally. The distributions of out-of-plane displacement over the loading procedure were also obtained. Furthermore, a comparison of measurement accuracy between two-dimensional digital image correlation (2D-DIC) and 3D-DIC was also performed. Due to the theoretical restriction, the measurement accuracy of 2D-DIC decreases with the increase of deformation. A maximum discrepancy of about 20% with 3D-DIC was observed in this work. Therefore, 3D-DIC is actually more essential for the high-accuracy investigation of PLC effect.
Zhongjia Chen - One of the best experts on this subject based on the ideXlab platform.
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three types of portevin Le Chatelier effects experiment and modelling
Acta Materialia, 2007Co-Authors: Huifeng Jiang, Qingchuan Zhang, Zhenyu Jiang, Zhongjia Chen, Xuedong Chen, Jinghong FanAbstract:Abstract By employing the dynamic digital speckLe pattern interferometry (DSPI) technique, three types of Portevin–Le Chatelier (PLC) effects are investigated systematically, with emphasis on the temporal and spatial dynamic features. A new model based on the dynamic strain aging (DSA) mechanism is proposed, and three types of PLC effects at different applied strain rates are reproduced by it when the spatial coupling is included. The dynamic interaction between dislocation and diffusing solutes is also studied through the developed constitutive model. The results self-consistently exhibit three branches of the dislocation–solute interaction, two stabLe branches at low and high strain rate (or dislocation velocity), which correspond to the effective aging or unpinning of dislocation, respectively, and a metastabLe one at the intermediate strain rate, where negative strain rate sensitivities result from the dynamic strain aging.
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on the propagation and pulsation of portevin Le Chatelier deformation bands an experimental study with digital speckLe pattern metrology
International Journal of Plasticity, 2005Co-Authors: Qingchuan Zhang, Huifeng Jiang, Zhenyu Jiang, Zhongjia ChenAbstract:Abstract The Portevin-Le Chatelier (PLC) effect is closely associated with inhomogeneous deformation, which is characterized by the band of strain localization. In this work, the spatio-temporal dynamics of the Portevin-Le Chatelier deformation bands are investigated by a novel digital speckLe pattern metrology technique consisting of digital speckLe pattern interferometry (DSPI) and digital speckLe correlation (DSC). A series of tension process of a commercial aluminum alloy (A2017) under different imposed strain rates in a range from 10 −6 to 10 −3 s −1 are monitored in real time with this technique. The formation of the PLC band, the evolution of the band structure and the propagation of the band are visualized and followed by fringe patterns. The distribution of the deformation in the specimen containing the band is measured precisely. It is shown that even for a tensiLe test, an elastic shrinkage deformation, which is caused by the avalanche-like shearing deformation within the band, occurs outside the band.
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spatial characteristics of the portevin Le Chatelier deformation bands in al 4 at cu polycrystals
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: Zhenyu Jiang, Huifeng Jiang, Qingchuan Zhang, Zhongjia ChenAbstract:The Portevin-Le Chatelier (PLC) effect represents a typical plastic instability in many metallic alloys of industrial interest. In space domain, this effect commonly consists of repeated nucLeation and propagation of band structure, in which the plastic deformation concentrates, along the tensioned specimen. In this paper, a novel digital speckLe pattern metrology technique including digital speckLe pattern interferometry (DSPI) and digital speckLe correlation (DSC) has been applied to investigate the spatial features (geometrical shape, localized plastic deformation in band) and dynamic characteristics (propagation of the bands, details of the band migration) of the PLC deformation bands in Al-4 at%Cu polycrystals simultaneously and quantitatively.
K J Kurzydlowski - One of the best experts on this subject based on the ideXlab platform.
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statistical analysis of the portevin Le Chatelier effect in inconel 718 at high temperature
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: P Maj, Joanna Zdunek, Jaroslaw Mizera, Maciej Gizynski, K J KurzydlowskiAbstract:Abstract The Portevin–Le Chatelier effect manifests itself as an unstabLe plastic flow which occurs during tensiLe tests of some dilute materials in a certain range of temperatures and strain rates. This phenomenon is also exceptionally intense in nickel based superalloys used in the aerospace industry. The aim of this research was to investigate the Portevin–Le Chatelier effect in Inconel 718 solution strengthened superalloy. The tested material was subjected to tensiLe tests carried out within the temperature range 250–600 °C with three different strain rates 2×10 −3 s −1 , 10 −2 s −1 and 5×10 −2 s −1 . The strain curves were analyzed in terms of intensity and statistical behavior. A quantitative method to describe the phenomenon was used in the study. The results indicate the presence of cLear trends with temperature and strain rates. Additional optical observations were carried out to assess the changes of the microstructure.
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the effect of a notch on the portevin Le Chatelier phenomena in an al 3mg model alloy
Materials Characterization, 2014Co-Authors: P Maj, Joanna Zdunek, Jaroslaw Mizera, K J KurzydlowskiAbstract:Abstract The aim of this research was to investigate the influence of a geometrical notch on the Portevin–Le Chatelier effect. This phenomenon manifests itself as the serrated stress–strain curve obtained for certain materials when they undergo plastic deformation during tensiLe tests. The Portevin–Le Chatelier effect can often be observed in aluminum alloys especially those with an addition of magnesium. The material examined in the present experiments was a model Al–3Mg alloy. SampLes were prepared with notches cut in the specimens with different depths and shapes. The results cLearly indicate that the notch has a significant influence on the Portevin–Le Chatelier effect. With increasing notch depth, the stress amplitude of the serrations increases together with their frequency and the course of the serrations changes.
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digital image correlation investigation of portevin Le Chatelier effect in an aluminium alloy
Materials Characterization, 2008Co-Authors: Joanna Zdunek, Jaroslaw Mizera, Tomasz Brynk, Zbigniew Pakiela, K J KurzydlowskiAbstract:Abstract The Portevin–Le Chatelier (PLC) effect in an Al–4.5 Mg–0.7Mn alloy was studied using the Digital Image Correlation technique. The results provide a new insight into the development of deformation bands related with the stress oscillations observed during the tensiLe testing of the alloy.
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on the anisotropy of the portevin Le Chatelier plastic instabilities in al li cu zr alloy
Scripta Materialia, 2001Co-Authors: Jaroslaw Mizera, K J KurzydlowskiAbstract:Abstract The anisotropy of the Portevin–Le Chatelier effect in the Al–Li–Cu–Zr alloy is reported. A new method for the quantification of the observed differences is proposed. The differences in intensity of serration are discussed in terms of the anisotropy of the microstructure of the material.