Deformation Behavior And Internal Stress Of Icosahedral Al-Pd-Mn With Decagonal Phase Lamellae At Elevated Temperatures

1998 ◽  
Vol 553 ◽  
Author(s):  
H. Hirai ◽  
T. Tomita ◽  
F. Yoshida ◽  
H. Nakashima
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Internal Stress ◽  
Stress Exponent ◽  
Deformation Behavior ◽  
Elevated Temperatures ◽  
Initial Strain Rate ◽  
Decagonal Phase ◽  
Thermally Activated ◽  
High Internal Stress

AbstractFine decagonal phase lamellae-bearing icosahedral Al-Pd-Mn quasicrystals were tested compressionally at temperatures of 997 to 1073 K and initial strain rate of 3 × 10−5. to I × 10−4 S−1, and stress relaxation tests were performed at various stages of deformation. The results confirmed the thermally activated nature of deformation, and the stress exponent of strain rate was around 4. Internal stress for deformation estimated by Kikuchi's method reached 50 to 90 % of applied stress. The effective stress exponent of strain rate was revealed to be about 1.3. At least a part of high internal stress was attributable to complicated dislocation microstructure.

Deformation Behaviour of an AX41 Magnesium Alloy at Elevated Temperatures

2007 ◽  
Vol 567-568 ◽  
pp. 321-324
Author(s):  
Zuzanka Trojanová ◽  
Pavel Lukáč ◽  
Zoltán Száraz
Keyword(s):  
Magnesium Alloy ◽  
Stress Relaxation ◽  
Strain Rate ◽  
Uniaxial Tension ◽  
Elevated Temperatures ◽  
Deformation Behaviour ◽  
Initial Strain Rate ◽  
Testing Temperature ◽  
Tension Tests ◽  
Deformation Processes

The deformation behaviour of the ternary magnesium alloy AX41 (4%Al-1%Ca-balance Mg) were investigated in uniaxial tension tests at temperatures between 20 and 300 °C and at an initial strain rate ranging in the order 10-4 s-1. The yield stress of the alloy is very sensitive to the testing temperature. Stress relaxation tests were performed with the aim to reveal physical base of deformation processes.

Stress Relaxation in Selected Magnesium Alloys

2007 ◽  
Vol 345-346 ◽  
pp. 1613-1616 ◽  
Author(s):  
Zuzanka Trojanová ◽  
Pavel Lukáč ◽  
Kyung Hyun Kim
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Internal Stress ◽  
Magnesium Alloys ◽  
Test Temperature ◽  
Room Temperature ◽  
Initial Strain Rate ◽  
Initial Strain ◽  
Relaxation Phenomena ◽  
Relaxation Curves

The stress relaxation phenomena in magnesium alloys, containing Al, Sr and Ca solutes have been investigated. The samples were deformed at a constant initial strain rate at various temperatures between room temperature and 300 °C. Stress relaxation, i.e. a decrease in the stress with time, was measured at various stresses and at various temperatures. The stress relaxation curves were analysed as a function of the internal stress at the beginning of the relaxation and the test temperature.

On Phenomenon of Superplasticity in Fe3AL with Large Grains

1994 ◽  
Vol 364 ◽  
Author(s):  
Aidang Shan ◽  
Dongliang Lin
Keyword(s):  
Tensile Test ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Initial Strain Rate ◽  
Optical Microscope ◽  
Al Alloys ◽  
Initial Strain ◽  
Atomic Percent ◽  
Maximum Elongation ◽  
Grain Sizes

AbstractA variety of Fe3Al alloys including Fe-25Al, Fe-28Al, Fe-28Al-4Cr and Fe-28Al-2Ti (all in atomic percent) have been investigated by tensile test to find if these alloys could have superplasticity at elevated temperatures, the results revealed that all these alloys exhibited large elongations when the temperature is higher than 600°C. At 850°C , under appropriate initial strain rate, the elongation is all above 300%. For Fe-28Al-2Ti, the maximum elongation reached 585%. Maximum m values are all above 0.3. Initial grain sizes are bigger than 100μm but became finer after deformation. Fracture happened with necking but no cavities were found under optical microscope. Characteristics of this phenomenon were summarized and discussed.

Thermally Activated Dislocation Motion in an AS21 Alloy and Alloy Reinforced with Short Ceramic Fibres Studied at Elevated Temperatures

2013 ◽  
Vol 592-593 ◽  
pp. 71-74
Author(s):  
Zuzana Zdražilová ◽  
Zuzanka Trojanová ◽  
Kristián Máthis ◽  
Pavel Lukáč
Keyword(s):  
Magnesium Alloy ◽  
Stress Relaxation ◽  
Applied Stress ◽  
Elevated Temperatures ◽  
Activation Volume ◽  
Activation Enthalpy ◽  
Dislocation Motion ◽  
Thermally Activated ◽  
Effective Components ◽  
Thermally Activated Process

AS21 magnesium alloy (2.1Al-1Si-balance Mg in wt.%) and the alloy reinforced with short δ-Al2O3fibres (Saffil®) were deformed in compression at temperatures between 23 and 300 °C. Stress relaxation tests were performed in order to reveal features of the thermally activated dislocation motion. Internal and effective components of the applied stress have been estimated. The activation volume decreases with increasing effective stress. The values of the activation volume and the activation enthalpy indicate that the main thermally activated process in the alloy as well as in the composite is the dislocation motion in non-compact planes.

Determination of the internal stress and dislocation velocity stress exponent with indentation stress relaxation test

2008 ◽  
Vol 23 (9) ◽  
pp. 2486-2490 ◽  
Author(s):  
B.X. Xu ◽  
X.M. Wang ◽  
Z.F. Yue
Keyword(s):  
Stress Relaxation ◽  
Internal Stress ◽  
Stress Exponent ◽  
Indentation Test ◽  
Dislocation Velocity ◽  
Attractive Potential ◽  
Integral Constant ◽  
Properties Of Materials ◽  
Relaxation Curves

Indentation stress relaxation tests were carried out on high-purity polycrystalline copper specimens at room temperature with a flat cylindrical indenter. The experimental results showed that the resulting load-time relaxation curves can be described by a power law, which coupled an internal stress and an integral constant between the effective stress and relaxation time. Then the internal stress, integral constant, and dislocation velocity stress exponent can be extracted from load relaxation curves. The derived values from this way were consistent with the results of conventional uniaxial compression stress relaxation tests. These agreements are not only useful to understand deformation (dislocation) mechanisms under the indenter, but also exhibit an attractive potential of measuring nano/micromechanical properties of materials by indentation test.

Stress Relaxation in an AZ31 Magnesium Alloy

2011 ◽  
Vol 465 ◽  
pp. 101-104 ◽  
Author(s):  
Pavel Lukáč ◽  
Zuzanka Trojanová
Keyword(s):  
Magnesium Alloy ◽  
Stress Relaxation ◽  
Deformation Temperature ◽  
Room Temperature ◽  
Activation Volume ◽  
Initial Strain Rate ◽  
Az31 Magnesium Alloy ◽  
Thermally Activated ◽  
Relaxation Curves ◽  
Thermally Activated Process

Stress relaxation tests have been used in order to determine parameters of a possible thermally activated process in AZ31 magnesium alloy. The samples were deformed at a constant initial strain rate of 6.7x10-5 s-1 at various temperatures between room temperature and 300 °C. Stress relaxation, i.e. a decrease in the stress with time, was measured at various stress levels and at various temperatures. An analysis of the stress relaxation curves enabled to estimate the internal stress as a function of the strain and the test temperature. It has been shown that the activation volume is a function of the effective stress independently of the deformation temperature.

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