Features of switching autowaves of localized plasticity in FCC alloy

2021 ◽  
pp. 27-32
Author(s):  
V.I. Danilov ◽  
◽  
V.V. Gorbatenko ◽  
L.V. Danilova ◽  
D.V. Orlova ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Test Machine ◽  
Scale Level ◽  
Yield Plateau ◽  
Deformation Processes ◽  
Fcc Alloy ◽  
Lüders Band ◽  
Applied Stresses ◽  
Kinetics Of ◽  
Discrete Motion

The kinetics of deformation processes at the yield plateau in the aluminum alloy 1550 studied. It is established that in the general case, the motion of the Lüders band fronts occurs discretely and only in the phase of sample unloading. Continuous motion of the deformation fronts is possible if the rate of relaxation of the applied stresses due to the test machine is greater than or equal to the rate of their decline, controlled by internal processes at a lower scale level. The discrete motion of the Lüders fronts in the 1550 alloy suggests that they are not pure autowaves of switching.

In situ observation of the martensitic transformation in (Mg,Y)-PSZ

1986 ◽  
Vol 44 ◽  
pp. 500-501
Author(s):  
R-R. Lee
Keyword(s):  
Martensitic Transformation ◽  
High Strength ◽  
Nucleation And Growth ◽  
In Situ Observation ◽  
Considerable Potential ◽  
Transmission Electron ◽  
Structural Applications ◽  
Applied Stresses ◽  
Kinetics Of

Partially-stabilized ZrO2 (PSZ) ceramics have considerable potential for advanced structural applications because of their high strength and toughness. These properties derive from small tetragonal ZrO2 (t-ZrO2) precipitates in a cubic (c) ZrO2 matrix, which transform martensitically to monoclinic (m) symmetry under applied stresses. The kinetics of the martensitic transformation is believed to be nucleation controlled and the nucleation is always stress induced. In situ observation of the martensitic transformation using transmission electron microscopy provides considerable information about the nucleation and growth aspects of the transformation.

Microstructure Evolution and Coarsening Mechanism of 7075 Semi-Solid Aluminum Alloy Pre-Deformed by ECAP Method

2016 ◽  
Vol 256 ◽  
pp. 294-300 ◽  
Author(s):  
Jin Long Fu ◽  
Yu Wei Wang ◽  
Kai Kun Wang ◽  
Xiao Wei Li
Keyword(s):  
Aluminum Alloy ◽  
Solid State ◽  
Ostwald Ripening ◽  
Liquid Fraction ◽  
Isothermal Holding ◽  
Angular Pressing ◽  
Average Grain Size ◽  
Semi Solid ◽  
Equiaxed Grains ◽  
Kinetics Of

To investigate the influence of refined grains on the microstructure of 7075 aluminum alloy in semi-solid state, a new strain induced melting activation (SIMA) method was put forward containing two main stages: pre-deformation with equal channel angular pressing (ECAP) method and isothermally holding in the semi-solid temperature range. The breaking up and growth mechanisms of the grains and kinetics of equiaxed grains coarsening during the semi-solid holding were investigated. The results showed that the average grain size after ECAP extrusion decreased significantly, e.g., microstructure with average globular diameter less than 5μm was achieved after four-pass ECAP extrusion. Obvious grain coarsening had been found during isothermal holding in the semi-solid state and the roundness of the grains increased with the increasing holding time. The proper microstructure of 66.8μm in diameter and 1.22 in shape factor was obtained under proper soaking condition (at 590°C for 15 min). Two coarsening mechanisms, namely, coalescence in lower liquid fraction and Ostwald ripening in higher liquid fraction contributed to the grain growth process.

Precipitation kinetics of 2519A aluminum alloy based on aging curves and DSC analysis

2014 ◽  
Vol 24 (10) ◽  
pp. 3076-3083 ◽  
Author(s):  
Yi-ping WU ◽  
Ling-ying YE ◽  
Yu-zhen JIA ◽  
Ling LIU ◽  
Xin-ming ZHANG
Keyword(s):  
Aluminum Alloy ◽  
Precipitation Kinetics ◽  
Dsc Analysis ◽  
Kinetics Of

Kinetics of grain growth in 2024-T3: An aerospace aluminum alloy

2009 ◽  
Vol 478 (1-2) ◽  
pp. 128-132 ◽  
Author(s):  
Zainul Huda ◽  
Tuan Zaharinie
Keyword(s):  
Aluminum Alloy ◽  
Grain Growth ◽  
Kinetics Of

Prediction of the Stress-Strain Response of the Ultrafine-Grained Materials Using Multi-Scale Analysis

2010 ◽  
Author(s):  
Mihaela Banu ◽  
Mitica Afteni ◽  
Alexandru Epureanu ◽  
Valentin Tabacaru
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Aluminum Alloy ◽  
Severe Plastic Deformation ◽  
Scale Analysis ◽  
Multi Scale ◽  
Ultrafine Grained ◽  
Deformation Processes ◽  
Ultrafine Grained Materials ◽  
Multi Scale Analysis

There are several severe plastic deformation processes that transform the material from microsized grains to the nanosized grains under large deformations. The grain size of a macrostructure is generally 300 μm. Following severe plastic deformation it can be reached a grain size of 200 nm and even less up to 50 nm. These structures are called ultrafine grained materials with nanostructured organization of the grains. There are severe plastic deformation processes like equal angular channel, high pressure torsion which lead to a 200 nm grain size, respectively 100 nm grain size. Basically, these processes have a common point namely to act on the original sized material so that an extreme deformation to be produced. The severe plastic deformation processes developed until now are empirically-based and the modeling of them requires more understanding of how the materials deform. The macrostructural material models do not fit the behavior of the nanostructured materials exhibiting simultaneously high strength and ductility. The existent material laws need developments which consider multi-scale analysis. In this context, the present paper presents a laboratory method to obtain ultrafine grains of an aluminum alloy (Al-Mg) that allows the microstructure observations and furthermore the identification of the stress–strain response under loadings. The work is divided into (i) processing of the ultrafine-grained aluminum alloy using a laboratory-scale process named in-plane controlled multidirectional shearing process, (ii) crystallographic analysis of the obtained material structure, (iii) tensile testing of the ultrafine-grained aluminum specimens for obtaining the true stress-strain behavior. Thus, the microscale phenomena are explained with respect to the external loads applied to the aluminum alloy. The proposed multi-scale analysis gives an accurate prediction of the mechanical behavior of the ultrafine-grained materials that can be further applied to finite element modeling of the microforming processes.

scholarly journals Heat-Induced Evolution of Phase Transformations in Tetrahydrofuran Hydrate-Bearing Sediment

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
X. H. Zhang ◽  
X. B. Lu ◽  
Z. M. Zheng ◽  
L. M. Zhang
Keyword(s):  
Phase Transformations ◽  
Hydrate Dissociation ◽  
Three Phase ◽  
Deformation Processes ◽  
Strata Deformation ◽  
Series Of Experiments ◽  
Similar Solutions ◽  
Hydrate Bearing Sediments ◽  
And Control ◽  
Kinetics Of

Heat conduction and phase transformations are basic physical-chemical process and control the kinetics of dissociation, fluid flow and strata deformation during hydrate dissociation in sediments. This paper presents a simplified analysis of the thermal process by assuming that the heat-induced evolution can be decoupled from flow and deformation processes. Self-similar solutions for one-, two- and three-phase transformation fronts are obtained. A series of experiments on THF-hydrate-bearing sediments was conducted to test the theory. The theoretical, numerical and experimental results on the evolution of hydrate dissociation front in the sediment are in good agreement.

High-temperature deformation and fracture of Bi–Sr–Ca–Cu–O superconductors

1994 ◽  
Vol 9 (3) ◽  
pp. 541-547 ◽  
Author(s):  
K.C. Goretta ◽  
E.J. Zamirowski ◽  
J.M. Calderoñ-Moreno ◽  
D.J. Miller ◽  
Nan Chen ◽  
...  
Keyword(s):  
Dislocation Motion ◽  
Steady State Creep ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Creep Response ◽  
Transmission Electron ◽  
Deformation And Fracture ◽  
Deformation Processes ◽  
Apparent Activation Energies ◽  
Kinetics Of

Dense polycrystalline Bi2Sr2Cu2Ox (2201), Bi2Sr2CaCu2Ox (2212), and (Bi, Pb)2Sr2Ca2Cu3Ox (2223) specimens were compressed in air at 730–835 °C. All of the materials exhibited an apparent steady-state creep response. Strain rate was proportional to stress to the 3.1–3.8 power. Apparent activation energies for the deformation processes were 520 ± 50 kJ/mole for the 2201, 630 ± 210 kJ/mole for the 2212, and 960 ± 210 kJ/mole for the 2223. Transmission electron microscopy revealed substantial generation and propagation of basal-plane dislocations during deformation. Few nonbasal-plane dislocations were observed. Intergranular fracture was evident in all deformed samples, and intragianular fracture was evident along the basal planes of some grains. It is suggested that the kinetics of fracture were determined by dislocation motion within the grains.

Kinetics of Deformation Processes in a High-Alloy Cast TWIP Steel Determined by Acoustic Emission and Scanning Electron Microscopy

2013 ◽  
Vol 592-593 ◽  
pp. 489-492
Author(s):  
Anja Weidner ◽  
Alexei Vinogradov ◽  
Alexei Lazarev ◽  
Horst Biermann
Keyword(s):  
Plastic Deformation ◽  
Acoustic Emission ◽  
Twip Steel ◽  
Tensile Deformation ◽  
Stacking Fault ◽  
Trip Effect ◽  
High Alloy ◽  
Deformation Processes ◽  
Kinetics Of ◽  
Alloy Cast

High-alloy cast CrMnNi steels exhibit depending on the chemical composition either transformation induced plasticity (TRIP-effect) or twinning induced plasticity (TWIP effect). Whereas the TRIP effect is caused by a martensitic phase transformation from the f.c.c austenitic phase into the b.c.c α-martensite phase via the formation of deformation bands with high stacking fault density the so-called ε-martensite, the TWIP effect is the result of mechanical twinning during plastic deformation. The occurrence of both effects as well as the underlying microstructural processes are strongly affected by the austenite stability, the stacking fault energy and/or the test temperature. However, the onset stress and the kinetics of these deformation processes are still unknown. The in-situ measurement of acoustic emission signals during the plastic deformation of materials is a powerful tool for the investigation of such dynamic microstructural processes and their kinetics. In the present study acoustic emission measurements were performed during tensile deformation at room temperature on a high-alloy cast TWIP steel. The AE investigations were completed by SEM investigations on the deformed specimens. The statistical and cluster analysis of acoustic emission signals reveals different patterns of acoustic emission signals, which are correlated with underlying microstructural processes.

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