scholarly journals A High-Strain-Rate Superplasticity of the Al-Mg-Si-Zr-Sc Alloy with Ni Addition

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2028
Author(s):  
Andrey Mochugovskiy ◽  
Anton Kotov ◽  
Majid Esmaeili Ghayoumabadi ◽  
Olga Yakovtseva ◽  
Anastasia Mikhaylovskaya
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Strain Rate Range ◽  
Zener Pinning ◽  
Nucleation Effect ◽  
Pinning Effect ◽  
Ni Addition ◽  
Elongation To Failure ◽  
Mean Size ◽  
High Temperature Tensile

The current study analyzed the effect of Ni content on the microstructure and superplastic deformation behavior of the Al-Mg-Si-Cu-based alloy doped with small additions of Sc and Zr. The superplasticity was observed in the studied alloys due to a bimodal particle size distribution. The coarse particles of eutectic origin Al3Ni and Mg2Si phases with a total volume fraction of 4.0–8.0% and a mean size of 1.4–1.6 µm provided the particles with a stimulated nucleation effect. The L12– structured nanoscale dispersoids of Sc- and Zr-bearing phase inhibited recrystallization and grain growth due to a strong Zener pinning effect. The positive effect of Ni on the superplasticity was revealed and confirmed by a high-temperature tensile test in a wide strain rate and temperature limits. In the alloy with 4 wt.% Ni, the elongation-to-failure of 350–520% was observed at 460 °C, in a strain rate range of 2 × 10−3–5 × 10−2 s−1.

Hot Deformation Behavior and Microstructural Evolution of Mg-Nd-Zn-Zr Magnesium Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 320-326 ◽  
Author(s):  
Wen Xiang Wu ◽  
Li Jin ◽  
Jie Dong ◽  
Zhen Yan Zhang ◽  
Wen Jiang Ding
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Hot Deformation ◽  
Fine Particles ◽  
Volume Fraction ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Average Size

The hot deformation behaviors and microstructural evolution of Mg-3.0Nd-0.2Zn-0.4Zr (wt. %, NZ30K) alloy were investigated by means of the isothermal hot compression tests at temperatures of 350-500 °C with strain rates of 0.001, 0.01, 0.1 and 1s-1. The results showed that the flow stress increased to a peak and then decreased which showed a dynamic flow softening. The flow stress behavior was described by the hyperbolic sine constitutive equation with an average activation energy of 193.8 kJ/mol. The average size of dynamically recrystallized grains of hot deformed NZ30K alloy was reduced by increasing the strain rate and/or decreasing the deformation temperature. A large amount of fine particles precipitated in the grains interior and at the grain boundaries when heated to the compression temperatures and soaked for 5min below 450 °C. However, the volume fraction of particles decreased significantly when soaked for 5 min at 500 °C, and the coarse particles precipitated mainly at the grain boundaries. Hot deformation at the temperature of 500 °C around and at the strain rate range of 0.1s-1 was desirable for NZ30K alloy.

High-Temperature Mechanical Properties of As-Extruded ZK60

2005 ◽  
Vol 488-489 ◽  
pp. 753-758
Author(s):  
Wei Wu ◽  
C.M. Hong ◽  
Li Jia Chen ◽  
Yue Wang ◽  
Lin Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Strain Rate ◽  
Initial Strain Rate ◽  
Offset Yield Strength ◽  
High Temperature Mechanical Properties ◽  
Fracture Behaviors ◽  
Elongation To Failure ◽  
Zk60 Alloy ◽  
High Temperature Tensile

High-temperature tensile and fracture behaviors of as-extruded ZK60 alloy were investigated. It was evident from the experiments that with decreasing temperature and increasing strain rate, the 0.2% offset yield strength and ultimate tensile strength of the alloy increased while the elongation to failure decreased. The flowing stress of as-extruded ZK60 alloy during plastic deformation was proportioned to the reciprocal of temperature. At the initial strain rate of 5×10-4s-1, the calculated active energy at 300°C was about 93.4 kJ/mol.

Superplastic deformation characteristics and constitution equation in rapidly solidified Mg–Al–Ga alloy

1996 ◽  
Vol 11 (11) ◽  
pp. 2731-2737 ◽  
Author(s):  
A. Uoya ◽  
T. Shibata ◽  
K. Higashi ◽  
A. Inoue ◽  
T. Masumoto
Keyword(s):  
Strain Rate ◽  
High Strain ◽  
High Strength ◽  
Tensile Tests ◽  
Strain Rate Range ◽  
Powder Metallurgy Method ◽  
Deformation Characteristics ◽  
Elongation To Failure ◽  
Rapidly Solidified ◽  
Aluminum And Magnesium Alloys

The hot deformation characteristics of a newly typed, high strength magnesium-based alloy, Mg–8.3 wt.% Al–8.1 wt.% Ga alloy, produced by rapidly solidified and powder metallurgy method have been investigated. Tensile tests were carried out at a temperature range from 523 to 623 K and a strain rate range from 10−4 to 1 s−1. Superplastic characteristics were found and, especially, a maximum elongation-to-failure of 1080% was obtained at 573 K and at a relatively high strain rate of 10−2 s−1. Because of the presence of fine microstructures at high temperatures, the optimum superplastic strain rate of the Mg–Al–Ga alloy was higher than that of the reported conventional superplastic aluminum and magnesium alloys.

scholarly journals Effect of twinning and Al-Nd phase on dynamic recrystallization in rolled Mg-Al-Zn-Nd alloy at the moderate strain rate

2021 ◽  
Author(s):  
Xiaoming Cui ◽  
Zhengguang Wang ◽  
Zhilei Yu ◽  
Fei Liu ◽  
Xueping Zhao ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Rolling ◽  
Electron Backscatter Diffraction ◽  
Energy Dispersive Spectrometer ◽  
Strain Rate Range ◽  
Nucleation Effect ◽  
Backscatter Diffraction ◽  
Rolling Deformation

Abstract The dynamic recrystallization of Mg-Al-Zn-Nd alloy during moderate strain rate rolling was studied using electron backscatter diffraction (EBSD) and an energy dispersive spectrometer (EDS). The results showed three kinds of twinnings produced in the alloy in the strain rate range of 4.2 s-1 ~ 7.3 s-1, including {101 ̅2} extension twinning, {101 ̅1} contraction twinning, and {101 ̅1}-{101 ̅2} double twinning. The extension twinnings decreased gradually with the increase of strain rate. The dynamic recrystallization mechanisms during hot rolling under moderate strain rate conditions mainly include grain boundary nucleation, twinning nucleation, and secondary particle assistant nucleation. The dynamic recrystallization mechanism induced by twinning is mainly {101 ̅1}-{101 ̅2} double twinnings. In addition, the strain value near the Al-Nd phase and grain boundary is higher than in grain. The Al-Nd particles in Mg-Al-Zn-Nd alloy play an auxiliary nucleation effect on dynamic recrystallization during hot rolling deformation.

scholarly journals Modeling of Dynamic Recrystallization Behavior of As-Extruded AM50 Magnesium Alloy during Hot Compression by a Cellular Automaton Method

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 75
Author(s):  
Dayu Shu ◽  
Jing Wang ◽  
Menghao Jiang ◽  
Gang Chen ◽  
Liwei Lu ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Cellular Automaton ◽  
Volume Fraction ◽  
Strain Rate Range ◽  
Dynamic Recrystallization Behavior ◽  
Ca Model ◽  
Cellular Automaton Method ◽  
Experimental Values

The dynamic recrystallization (DRX) behavior of as-extruded AM50 magnesium alloy was modelled and simulated by a cellular automaton (CA) method. Isothermal compression experiments were conducted, and the characteristic parameters in the CA model were obtained by the testing stress–strain flow curves in a wide temperature range of 250–450 °C and strain rate range of 0.001–10 s−1. The flow stress, DRX volume fraction and DRX grain size of the as-extruded AM50 magnesium alloy were predicted by CA simulation. The results showed that the DRX behavior of the studied magnesium alloy was susceptive with the temperature and strain rate; meanwhile, the prediction results were approximate to the experimental values, indicating that the developed CA model can make a confident estimation on the DRX behavior of the as-extruded AM50 magnesium alloy in high temperature conditions.

scholarly journals On the Superplastic Deformation in Vanadium-Alloyed High-Nitrogen Steel

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 27 ◽  
Author(s):  
Elena Astafurova ◽  
Valentina Moskvina ◽  
Marina Panchenko ◽  
Galina Maier ◽  
Eugene Melnikov ◽  
...  
Keyword(s):  
Strain Rate ◽  
Tensile Deformation ◽  
Thermomechanical Processing ◽  
Rate Sensitivity ◽  
Grain Boundary Sliding ◽  
Strain Rate Range ◽  
High Nitrogen ◽  
Nitrogen Steel ◽  
Sliding Mechanism ◽  
Elongation To Failure

The experimental evidence for the realization of a superplastic behavior with 900% elongation in V-alloyed high-nitrogen austenitic Fe-19Cr-22Mn-1.5V-0.3C-0.6N steel was proposed. Using thermomechanical processing, a misoriented grain/subgrain austenitic microstructure with a high density of deformation-assisted defects and precipitates was developed in the steel. During high-temperature tensile deformation in a temperature interval from 850 to 1000 °C and strain-rate range from 4 × 10−4 s−1 to 6 × 10−3 s−1, this microstructure demonstrated the characteristics of superplastic flow: elongation in the interval 400–900%, strain-rate sensitivity exponent m = 0.40–0.49, grain boundary sliding mechanism. The maximum elongation to failure (900%) was reached at deformation temperature 950 °C and strain rate 4 × 10−4 s−1.

scholarly journals Superplasticity of Ti-6Al-4V Titanium Alloy: Microstructure Evolution and Constitutive Modelling

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1756 ◽  
Author(s):  
Ahmed O. Mosleh ◽  
Anastasia V. Mikhaylovskaya ◽  
Anton D. Kotov ◽  
James S. Kwame ◽  
Sergey A. Aksenov
Keyword(s):  
Strain Rate ◽  
Microstructural Evolution ◽  
Deformation Temperature ◽  
Superplastic Deformation ◽  
Deformation Behaviour ◽  
Strain Rate Range ◽  
Grain Structure ◽  
Rate Range ◽  
Temperature Range ◽  
Elongation To Failure

Determining a desirable strain rate-temperature range for superplasticity and elongation-to-failure are critical concerns during the prediction of superplastic forming processes in α + β titanium-based alloys. This paper studies the superplastic deformation behaviour and related microstructural evolution of conventionally processed sheets of Ti-6Al-4V alloy in a strain rate range of 10–5–10–2 s–1 and a temperature range of 750–900 °C. Thermo-Calc calculation and microstructural analysis of the as-annealed samples were done in order to determine the α/β ratio and the grain size of the phases prior to the superplastic deformation. The strain rate ranges, which corresponds to the superplastic behaviour with strain rate sensitivity index m ˃ 0.3, are identified by step-by-step decreasing strain rate tests for various temperatures. Results of the uniaxial isothermal tensile tests at a constant strain rate range of 3 × 10−4–3 × 10−3 s−1 and a temperature range of 800–900 °C are presented and discussed. The experimental stress-strain data are utilized to construct constitutive models, with the purpose of predicting the flow stress behaviour of this alloy. The cross-validation approach is used to examine the predictability of the constructed models. The models exhibit excellent approximation and predictability of the flow behaviour of the studied alloy. Strain-induced changes in the grain structure are investigated by scanning electron microscopy and electron backscattered diffraction. Particular attention is paid to the comparison between the deformation behaviour and the microstructural evolution at 825 °C and 875 °C. Maximum elongation-to-failure of 635% and low residual cavitation were observed after a strain of 1.8 at 1 × 10−3 s−1 and 825 °C. This temperature provides 23 ± 4% β phase and a highly stable grain structure of both phases. The optimum deformation temperature obtained for the studied alloy is 825 °C, which is considered a comparatively low deformation temperature for the studied Ti-6Al-4V alloy.

High Strain Rate Superplasticity in an Al-Mg-Sc-Zr Alloy Produced by Equal Channel Angular Pressing and Subsequent Cold and Warm Rolling

2012 ◽  
Vol 710 ◽  
pp. 223-228 ◽  
Author(s):  
Elena Avtokratova ◽  
Oleg Sitdikov ◽  
Oksana Mukhametdinova ◽  
Michael Markushev
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Equal Channel Angular Pressing ◽  
Volume Fraction ◽  
Warm Rolling ◽  
Strain Rate Range ◽  
Ambient Temperatures ◽  
Angular Pressing ◽  
The Difference ◽  
Zr Alloy

Superplastic (SP) properties of an Al−5%Mg−0.2%Sc−0.08%Zr alloy subjected to equal channel angular pressing (ECAP) at T=325°C with an effective stain of ~ 8 and subsequent rolling at the same and ambient temperatures were studied. It has been shown that the formation of ultrafine grained (UFG) structure with the grain size of about 1 μm and the volume fraction 0.6-0.7 under ECAP resulted in exceptionally high SP ductilities in a wide temperature - strain rate range. Maximum elongations ~3300% appeared at 475°C and the strain rate () of 5.6×10-2s-1. Subsequent warm rolling with a total reduction of 86% led to increased to 0.8-0.85 volume fraction of ultrafine grains with no changes in grain size. Cold rolling with reduction of 80%, in contrast, provided a heavily deformed structure with high dislocation density. In spite of the difference in the alloy microstructures, the SP properties in both rolled conditions were close to similar. The both states exhibited SP behavior with maximum elongation of ~ 2800% at 520°C and = 1.4 ×10-2s-1.

Cavitation in a Uniaxially deformed Superplastic Al-Mg Alloy

1999 ◽  
Vol 601 ◽  
Author(s):  
D. H. Bae ◽  
A. K. Ghosh
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Cavity Growth ◽  
Tensile Tests ◽  
Strain Rate Range ◽  
Cavity Volume ◽  
Fine Grained ◽  
Cu Alloy ◽  
Deformable Particles ◽  
The Matrix

AbstractCavitation caused by superplastic straining of a fine-grained Al-Mg-Mn-Cu alloy under uniaxial tension has been systematically evaluated. Tensile tests were conducted in the strain-rate range of 10−4s−1 to 10−2s−1 and in the temperature range of 450°C to 550°C. Measurements of the number and size of cavities were made by image analysis through optical microscopy on tested specimens. With increasing imposed strain, the cavity population density increases. Cavity growth has been found to be primarily due to the plastic deformation of the matrix. These results are characterized by the total volume fraction of cavities which is found to increase exponentially with strain. However, the dependencies of cavity volume fraction on strain-rate and temperature are not straightforward and the notion of just a few large cavities controlling the total cavity volume is not always true. Attempts to explain these complex dependencies have been carried out based on the concepts of debonding between the matrix and non-deformable particles, the continuous nucleation of new cavities, and plasticity-based cavity growth for large cavities.

Observation of dislocations in dynamically loaded Cu-SiO2

1986 ◽  
Vol 44 ◽  
pp. 424-425
Author(s):  
D. S. Pritchard
Keyword(s):  
Electron Microscope ◽  
Strain Rate ◽  
Single Crystal ◽  
Transmission Electron Microscope ◽  
Volume Fraction ◽  
Screw Dislocations ◽  
Spherical Inclusions ◽  
Transmission Electron ◽  
Crystal Dispersion ◽  
Strain Rate Loading

The effect of varying the strain rate loading conditions in compression on a copper single crystal dispersion-hardened with SiO2 particles has been examined. These particles appear as small spherical inclusions in the copper lattice and have a volume fraction of 0.6%. The structure of representative crystals was examined prior to any testing on a transmission electron microscope (TEM) to determine the nature of the dislocations initially present in the tested crystals. Only a few scattered edge and screw dislocations were viewed in those specimens.

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