Peculiar Spatiotemporal Behavior of Unstable Plastic Flow in an AlMgMnScZr Alloy with Coarse and Ultrafine Grains

Abstract

Abstract:The work addresses the effects of nanosize particles and grain refinement on the patterns of stress serrations and kinematics of deformation bands associated with the Portevin-Le Chatelier instability of plastic flow. Ultra-fine-grained microstructure was obtained using equal-channel angular pressing of the initial coarse-grained alloy. Tensile tests were carried out on flat specimens at strain rates in the range from 3 × 10 −5 to 1.4 × 10 −2 s −1 . Using local extensometry techniques, it was found that the presence of nanoscale precipitates promotes quasi-continuous propagation of deformation bands in the entire strain-rate range. The grain refinement leads to a transition to relay-race propagation at high strain rates and static strain localization at low rates. The results are discussed from the viewpoint of competition between various dynamical modes of plastic deformation associated with collective dynamics of dislocations.

Complexity and Anisotropy of Plastic Flow of α-Ti Probed by Acoustic Emission and Local Extensometry

“…Indeed, the presence of fluctuations in these figures means that such a conclusion is only valid globally. A magnification of such maps ( Figure 7 ) shows that these fluctuations generate complex structures including not only an apparent disorder but even wavy structures similar to various patterns observed in metals with cubic symmetry (e.g., [ 16 , 29 , 30 ]).…”

Effect of Multidirectional Forging on the Grain Structure and Mechanical Properties of the Al–Mg–Mn Alloy

“…Ultrafine grain (UFG) aluminum-based alloys have potential for use in industrial applications, due to their superior mechanical properties, such as strength-to-weight ratio, strength, ductility, and fatigue toughness [1,2,3,4,5]. An additional advantage of the UFG materials is their ability to be deformed into complex-shaped parts by superplastic forming (SPF) [6,7,8,9].…”

Synthesis and Properties of Bulk Nanostructured Metallic Materials

“…This research was the first attempt to understand how the UFG microstructure of biomedical titanium affects chemical composition changes of its surface, providing a potential method to improve bio-bonding between an implant and surrounding tissue. The article by Zhemchuzhnikova et al [3] presents the investigation of the Portevin-Le Chatelier (PLC) effect in an ECAP Al 5024 alloy (Al-Mg-Mn-Sc-Zr) with UFG microstructure at various strain rates. To examine behavior of PLC bands, the authors performed two different techniques, local extensometry and 2D digital image correlation (DIC).…”