Effect of initial textures on deformation mechanisms and texture evolutions of Zrα polycrystals deformed by channel-die compression tests

ABSTRACTWe present a study of the deformation mechanism of decagonal Al73Ni10Co17 quasicrystals by means of transmission electron microscopy. We performed compression tests on single-quasicrystalline samples in three different orientations: with the compression axis parallel to, inclined by 45 ° and perpendicular to the tenfold axis of the decagonal quasicrystal. The deformed samples reveal characteristic orientation-dependent dislocation structures leading us to the conclusion that fundamentally different deformation mechanisms are involved in plastic deformation in the three deformation geometries. We explicitly identified the Burgers vectors of the dislocations as interatomic vectors in the structure of decagonal Al-Ni-Co.

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Critical assessment of CuZn39Pb2 processing maps

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) ◽

10.1515/ijmr-2020-1110511 ◽

2020 ◽

Vol 111 (5) ◽

pp. 439-448

Author(s):

Jing Yin ◽

Shiqing Wu ◽

Zhenlun Song ◽

Cheng Xu ◽

Qi Cui

Keyword(s):

Continuous Casting ◽

Process Parameters ◽

Processing Map ◽

Flow Behavior ◽

Deformation Mechanisms ◽

Instability Criterion ◽

Strain Rates ◽

Processing Maps ◽

Compression Tests ◽

Different Strains

Abstract Isothermal hot compression tests of the CuZn39Pb2 continuous casting bar were carried out at 650 - 750 °C and strain rates of 0.1 - 50 s-1. After the experimental data were obtained, processing maps were constructed and discussed on the basis of the Prasad, Murty and Malas instability criteria to critically evaluate the flow behavior of the CuZn39Pb2 continuous casting bar. The microstructure suggested that the processing map based on the Murty instability criterion was suitable for optimizing the process parameters of the CuZn39Pb2. The relationships between the characteristics of processing maps and the deformation mechanisms under different strains were analyzed on the basis of Murty instability criterion. Considering the theoretical analysis results and energy consumption economy, 690 °C ≤ T ≤ 720 °C with 1 s-1 ≤ έ ≤ 3 s-1 are the best process parameters for CuZn39Pb2 forging.

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Influence of Temperature and Plastic Strain on Deformation Mechanisms and Kink Band Formation in Homogenized HfNbTaTiZr

Crystals ◽

10.3390/cryst11020081 ◽

2021 ◽

Vol 11 (2) ◽

pp. 81

Author(s):

Hans Chen ◽

Theresa Hanemann ◽

Sascha Seils ◽

Daniel Schliephake ◽

Aditya Srinivasan Tirunilai ◽

...

Keyword(s):

Plastic Deformation ◽

Plastic Strain ◽

Kink Band ◽

Deformation Mechanisms ◽

Large Temperature ◽

Plastic Strains ◽

Compression Tests ◽

Band Formation ◽

Influence Of Temperature ◽

Temperature Range

Due to its outstanding ductility over a large temperature range, equiatomic HfNbTaTiZr is well-suited for investigating the influence of temperature and plastic strain on deformation mechanisms in concentrated, body centered cubic solid solutions. For this purpose, compression tests in a temperature range from 77 up to 1073 K were performed and terminated at varying plastic strains for comparison of plastic deformation behavior. The microstructure and chemical homogeneity of a homogenized HfNbTaTiZr ingot were evaluated on different length scales. The compression tests reveal that test temperature significantly influences yield strength as well as work hardening behavior. Electron backscatter diffraction aids in shedding light on the acting deformation mechanisms at various temperatures and strains. It is revealed that kink band formation contributes to plastic deformation only in a certain temperature range. Additionally, the kink band misorientation angle distribution significantly differs at varying plastic strains.

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Spongy bone deformation mechanisms

European Journal of Computational Mechanics ◽

10.13052/ejcm.18.67-79 ◽

2009 ◽

pp. 67-79

Author(s):

Fahmi Chaari ◽

Julien Halgrin ◽

Éric Markiewicz ◽

Pascal Drazetic

Keyword(s):

Strain Rate ◽

Rate Sensitivity ◽

Deformation Mechanisms ◽

Compression Tests ◽

Rate Dependency ◽

Compression Force ◽

Sample Shape ◽

Final Sample ◽

Constitutive Material ◽

Cylindrical Samples

In order to identify the spongy bone's mechanical behaviour, we performed compression tests on cylindrical samples. Experimental results show important dispersions and an unexpected inverse strain rate dependency at low range of loading velocities. The origin of the dispersions can be attributed to the combination of the architecture effect and the mechanical properties variation of the constitutive material. In order to understand the inverse strain rate sensitivity, we used a controlled constitutive material to build new equivalent samples with the spongy bone's architecture. These samples were subjected to compression tests. Numerical simulations of compression tests on the same architecture have been carried out with FE models built from μCt data. The obtained results are compared in term of final sample shape and the evolution of the compression force.

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Flow Stress Prediction and Hot Deformation Mechanisms in Ti-44Al-5Nb-(Mo, V, B) Alloy

Materials ◽

10.3390/ma11102044 ◽

2018 ◽

Vol 11 (10) ◽

pp. 2044 ◽

Cited By ~ 7

Author(s):

Tianrui Li ◽

Guohuai Liu ◽

Mang Xu ◽

Bingxing Wang ◽

Tianlian Fu ◽

...

Keyword(s):

Phase Transformation ◽

Flow Stress ◽

Strain Rate ◽

Hot Deformation ◽

Microstructural Analysis ◽

Constitutive Relationship ◽

Deformation Mechanisms ◽

Compression Tests ◽

Ann Model ◽

Stress Prediction

To elucidate the hot deformation characteristics of TiAl alloys, flow stress prediction, microstructural evolution and deformation mechanisms were investigated in Ti-44Al-5Nb-1Mo-2V-0.2B alloy by isothermal compression tests. A constitutive relationship using the Arrhenius model involving strain compensation and back propagation artificial neural network (BP-ANN) model were developed. A comparison of two models suggested that the BP-ANN model had excellent capabilities and was more accurate in predicting flow stress. Based on the microstructural analysis, bending and elongation of colonies, γ and B2 grains were the main microstructural constituents at low temperature and high strain rate. Dynamic recrystallization (DRX) of γ and dynamic recovery (DRY) of β/B2 were the main deformation mechanisms. With the increase of temperature and decrease of strain rate, phase transformation played an important role. The flake-like γ precipitates in B2 grains, and a coarsening of γ lamellae via α lath dissolution during compression were observed. Additionally, the flow softening process commenced with dislocation pile-up and formation of sub-grain boundaries, followed by grain refinement, twins and nano-lamellar nucleation. Continuous DRX and phase transformation promoted the formability of Ti-44Al-5Nb-1Mo-2V-0.2B alloy.

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Compressive Deformation Behavior of an Ultrafine/Nano Grained AZ31 Magnesium Processed by Accumulative Back Extrusion

Archives of Metallurgy and Materials ◽

10.1515/amm-2016-0260 ◽

2016 ◽

Vol 61 (3) ◽

pp. 1593-1600 ◽

Cited By ~ 1

Author(s):

S.M. Fatemi ◽

A. Zarei-Hanzaki ◽

H. Paul

Keyword(s):

Deformation Behavior ◽

Room Temperature ◽

Az31 Alloy ◽

Deformation Texture ◽

Deformation Mechanisms ◽

Compressive Deformation ◽

Compression Tests ◽

Texture Change ◽

Mean Grain Size ◽

The Mean

Abstract An AZ31magneium alloy was processed through accumulative back extrusion (ABE) process at 280 °C up to six passes. Compressive deformation behavior of the processed materials was studied by employing uniaxial compression tests at room temperature. The results indicated that grains of 80 nm to 1 µm size were formed during accumulative back extrusion, where the mean grain size of the experimental material was reduced by applying successive ABE passes. A deformation texture characterizing with the basal plane mainly lie inclined to the deformation axis was developed. Compressive yield and maximum compressive strengths were measured to increase by applying successive extrusion passes, while the strain-to-fracture dropped. The evolution of mechanical properties was explained relying on the grain refinement effect as well as texture change. It was described that the share of different deformation mechanisms and developing of shearing regions near the grain boundaries may influence the deformation behavior of the ultrafine/nano grained AZ31 alloy.

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Electron Microscopy of Shock Loaded Polycrystalline Beryllium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052547 ◽

1974 ◽

Vol 32 ◽

pp. 506-507 ◽

Cited By ~ 1

Author(s):

J. M. Galbraith ◽

L. E. Murr ◽

A. L. Stevens

Keyword(s):

Electron Microscopy ◽

Wave Propagation ◽

Structural Change ◽

Single Crystal ◽

Diffraction Pattern ◽

Shock Loading ◽

Slip Systems ◽

Compression Tests ◽

X Ray Diffraction ◽

X Ray

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.

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Dislocations in alumina deformed by prismatic slip

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100110179 ◽

1978 ◽

Vol 36 (1) ◽

pp. 606-607

Author(s):

J. Cadoz ◽

J. Castaing ◽

J. Philibert

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Basal Slip ◽

Prismatic Slip ◽

Compression Tests ◽

Thin Sections ◽

Burgers Vector ◽

Maximum Deformation ◽

Transmission Electron ◽

Mechanical Thinning

Plastic deformation of alumina has been much studied; basal slip occurs and dislocation structures have been investigated by transmission electron microscopy (T.E.M.) (1). Non basal slip has been observed (2); the prismatic glide system <1010> {1210} has been obtained by compression tests between 1400°C and 1800°C (3). Dislocations with <0110> burgers vector were identified using a 100 kV microscope(4).We describe the dislocation structures after prismatic slip, using high voltage T.E.M. which gives much information.Compression tests were performed at constant strainrate (∿10-4s-1); the maximum deformation reached was 0.03. Thin sections were cut from specimens deformed at 1450°C, either parallel to the glide plane or perpendicular to the glide direction. After mechanical thinning, foils were produced by ion bombardment. Details on experimental techniques can be obtained through reference (3).

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Effect Of Elevated Temperatures On Complete Concrete Deformation Diagrams

Promyshlennoe i Grazhdanskoe Stroitel stvo ◽

10.33622/0869-7019.2019.11.09-14 ◽

2019 ◽

pp. 9-14

Keyword(s):

Experimental Data ◽

Elastic Modulus ◽

Elevated Temperatures ◽

Peak Load ◽

Relative Deformation ◽

Deformation Characteristics ◽

Compression Tests ◽

Strain Behavior ◽

Different Temperatures ◽

Deformation Diagrams

The analysis of the previous results of the study on concrete stress-strain behavior at elevated temperatures has been carried out. Based on the analysis, the main reasons for strength retrogression and elastic modulus reduction of concrete have been identified. Despite a significant amount of research in this area, there is a large spread in experimental data received, both as a result of compression and tension. In addition, the deformation characteristics of concrete are insufficiently studied: the coefficient of transverse deformation, the limiting relative compression deformation corresponding to the peak load and the almost complete absence of studies of complete deformation diagrams at elevated temperatures. The two testing chambers provided creating the necessary temperature conditions for conducting studies under bending compression and tension have been developed. On the basis of the obtained experimental data of physical and mechanical characteristics of concrete at different temperatures under conditions of axial compression and tensile bending, conclusions about the nature of changes in strength and deformation characteristics have been drawn. Compression tests conducted following the method of concrete deformation complete curves provided obtaining diagrams not only at normal temperature, but also at elevated temperature. Based on the experimental results, dependences of changes in prism strength and elastic modulus as well as an equation for determining the relative deformation and stresses at elevated temperatures at all stages of concrete deterioration have been suggested.

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