Critical concentration of Mg addition for plastic instabilities in Al–Mg alloys

2000 ◽  
Vol 15 (5) ◽  
pp. 1037-1040 ◽  
Author(s):  
N. Q. Chinh ◽  
F. Csikor ◽  
Zs. Kovács ◽  
J. Lendvai
Keyword(s):  
Room Temperature ◽  
Loading Rate ◽  
Critical Concentration ◽  
Solute Concentration ◽  
Mg Alloys ◽  
Depth Sensing ◽  
Solute Content ◽  
Mg Addition ◽  
Constant Loading Rate ◽  
Al Mg Alloys

Plastic instabilities were investigated by the depth-sensing microhardness test in binary high-purity Al–Mg alloys with different Mg contents. During the tests the applied load was increased from 0 to 2000 mN at constant loading rate. The instabilities appeared as characteristic steps in the load–depth curves during indentation. It was shown that the occurrence and development of the plastic instabilities depend strongly on the solute content. Furthermore, the plastic instabilities occurred only when the solute concentration was larger than a critical value, C0. From room-temperature tests on Al–Mg alloys, C0 was found to be 0.86 wt% Mg. The critical concentration, which is necessary to get plastic instabilities, was also interpreted theoretically.

Solute concentration dependence of strength and plastic instabilities in Al-Mg alloys

2005 ◽  
Vol 20 (2) ◽  
pp. 331-337 ◽  
Author(s):  
Gy. Horváth ◽  
N.Q. Chinh ◽  
J. Lendvai
Keyword(s):  
Dislocation Line ◽  
Solute Concentration ◽  
Mg Alloys ◽  
Dynamic Strain ◽  
Solute Content ◽  
Serrated Flow ◽  
Indentation Tests ◽  
Power Law Function ◽  
Chatelier Effect ◽  
Al Mg Alloys

Characteristics of the dynamic strain aging (DSA) in the Portevin-Le Chatelier effect are experimentally investigated by dynamic indentation tests and numerically analyzed by using literature models. Experimental results obtained on Al–Mg alloys show that the occurrence and development of the plastic instabilities—serrated indentation—depend strongly on the solute content. During dynamic microindentation tests the amplitude of microhardness drops—similarly to the global hardness—and is changing as a power law function of Mg solute content with an exponent of 2/3. It has been shown that the term describing the effect of DSA in serrated flow is not proportional but rather a power expression of the local solute concentration, Cs, on the dislocation line with the exponent of 1/2. Together with this, the kinetics of solute segregation during DSA is controlled by the pipe diffusion.

Dynamic characterization of Portevin–Le Chatelier instabilities occurring in depth-sensing microhardness tests

2003 ◽  
Vol 18 (12) ◽  
pp. 2874-2881 ◽  
Author(s):  
G. Bérces ◽  
J. Lendvai ◽  
A. Juhász ◽  
N.Q. Chinh
Keyword(s):  
Dynamic Model ◽  
Contact Surface ◽  
Indentation Depth ◽  
Loading Rate ◽  
Experimental Setup ◽  
Dynamic Characterization ◽  
Depth Sensing ◽  
Constant Loading ◽  
Constant Loading Rate

Characteristic properties of plastic instabilities were studied using depth-sensing microhardness experiments on an Al–3.3 wt.% Mg alloy and computer simulations based on a macroscopic dynamic model of the experimental setup. A stepwise increase was observed in the indentation depth versus load (d-F) curves measured in constant loading rate mode, indicating hardness oscillations around a nearly constant value of the conventional dynamic microhardness. These oscillations were correlated with plastic instabilities starting from the contact surface between the sample and the indenter head. Taking into account the experimentally determined connection between the hardness oscillations and the indentation velocity, a dynamic model was proposed for the characterization of instability steps.

Influence of Mg Content, Grain Size and Strain Rate on Mechanical Properties and DSA Behavior of Al-Mg Alloys Processed by ECAP and Annealing

2014 ◽  
Vol 794-796 ◽  
pp. 870-875 ◽  
Author(s):  
Min Zha ◽  
Yan Jun Li ◽  
Ragnvald H. Mathiesen ◽  
Christine Baumgart ◽  
Hans J. Roven
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Strain Rate ◽  
Room Temperature ◽  
Uniform Elongation ◽  
Mg Alloys ◽  
Lower Strain Rate ◽  
Lower Strain ◽  
Mg Content ◽  
Al Mg Alloys

Ultrafine-grained (UFG) binary Al-xMg (x=1, 5 and 7 wt %) alloys were processed by equal channel angular pressing (ECAP) at room temperature via route Bccombined with inter-pass annealing. The effects of Mg content, grain size and strain rate on mechanical properties and dynamic strain aging (DSA) behaviour of the Al-Mg alloys upon tensile testing at room temperature were studied. An increase in Mg content from 5 to 7 wt % leads to a pronounced increase in strength and uniform elongation in both the as-homogenized and as-ECAP Al-Mg alloys. Thereby, the Al-7Mg alloy, either prior to or after ECAP processing, possess significantly higher strength and comparable or even higher uniform elongation than the more dilute Al-Mg alloys. However, the as-ECAP Al-Mg alloys exhibit significantly higher strength but little work hardening and hence rather limited uniform elongation. In general, decreasing grain size leads to significant increase in strength while dramatic decrease in ductility. Moreover, DSA serration amplitudes increase with reducing grain size in the micrometer range. However, the UFG Al-Mg alloys exhibit much less DSA effect than the micrometer scaled grain size counterparts, i.e. probably due to the high dislocation densities and special grain boundary features in the UFG materials. Also, the Al-Mg alloys, especially those with a UFG structure, exhibit higher strength and ductility at lower strain rate than at higher strain rate, due mainly to enhanced DSA effect and hence work hardening at a lower strain rate.

Induced Codeposition of Al–Mg Alloys in Lewis Acidic AlCl3–EMIC Room Temperature Molten Salts

2000 ◽  
Vol 29 (9) ◽  
pp. 1028-1029 ◽  
Author(s):  
Masatsugu Morimitsu ◽  
Nobutada Tanaka ◽  
Morio Matsunaga
Keyword(s):  
Molten Salts ◽  
Room Temperature ◽  
Mg Alloys ◽  
Induced Codeposition ◽  
Al Mg Alloys

Effect of a High Mg Solute Content on the Hot Workability of Al–Mg Alloys

2021 ◽  
Vol 21 (3) ◽  
pp. 1990-1995
Author(s):  
Jae-Cheol Lee ◽  
Hyeon-Woo Son ◽  
Sang-Wook Kim ◽  
Chang-Hee Cho ◽  
Yong-Jae Kim ◽  
...  
Keyword(s):  
Thermal Activation ◽  
Processing Map ◽  
Instability Region ◽  
Mg Alloys ◽  
Hot Workability ◽  
Flow Localization ◽  
Solute Content ◽  
Hot Torsion ◽  
Mg Content ◽  
Al Mg Alloys

The workability of Al–xMg alloys with a high Mg content (Al–6Mg, Al–8Mg, Al–9Mg) was evaluated by investigating the microstructure and processing map. Hot torsion tests were conducted in the range of 350–500 °C between 0.1 and 1 s−1. Constitutive equations were derived from various effective stress–strain curves, and the thermal activation energies for deformation obtained were 171 kJ/mol at Al–6Mg, 195 kJ/mol at Al–8Mg, and 220 kJ/mol at Al–9Mg. In the case of the processing map, the instability region, which widened with increasing Mg content, was due mainly to the influence of the Mg solute, which activated grain boundary cracking and flow localization.

Occurrence of plastic instabilities in dynamic microhardness testing

1998 ◽  
Vol 13 (6) ◽  
pp. 1411-1413 ◽  
Author(s):  
G. Bérces ◽  
N. Q. Chinh ◽  
A. Juháasz ◽  
J. Lendvai
Keyword(s):  
Room Temperature ◽  
Loading Rate ◽  
Testing Machine ◽  
Load Curve ◽  
Serrated Yielding ◽  
Microhardness Testing ◽  
Chatelier Effect ◽  
Computer Controlled ◽  
Solute Atoms ◽  
Constant Loading Rate

Plastic instabilities were observed to appear during dynamic ultramicrohardness testing of a solid solution Al–3.3 wt.% Mg alloy. The tests were carried out at room temperature with a Vickers hardness indenter in a computer-controlled dynamic ultramicrohardness testing machine. During the tests the applied load was increased from 0 to 2000 mN at constant loading rate. The instabilities appear as characteristic steps in the continuously recorded load-indentation depth curves. The physical basis for the occurrence of the instabilities is the interaction between moving dislocations and solute atoms, a phenomenon termed in the literature as serrated yielding, jerky flow, or Portevin-Le Châtelier effect. The instabilities start at a critical load, Fc, in the depth-load curve. Varying the loading rate, μ, by two orders of magnitude Fc was found to increase linearly with the loading rate.

scholarly journals Effect of magnesium addition on the vacancy-Mg binding free enthalpy in Al-Cr alloys

2002 ◽  
Vol 27 (0) ◽  
Author(s):  
Carlos Roberto Sobreira BEATRICE ◽  
Waldir GARLIPP ◽  
Mário CILENSE ◽  
Antonio Tallarico ADORNO
Keyword(s):  
Solid Solution ◽  
Electrical Resistivity ◽  
Mg Alloys ◽  
Free Enthalpy ◽  
Resistivity Measurements ◽  
Mg Addition ◽  
Mg Content ◽  
Al Mg Alloys ◽  
Magnesium Addition

The Mg-vacancy binding free enthalpy of Al-Cr solid solution alloys with Mg addition was calculated by electrical resistivity measurements. The obtained value is lower than that obtained for dilute Al-Mg alloys with almost the same Mg content and may be attributed to the diffusion of Mg.

The Effect of Mg on the Wetting Behavior of SiC-Al System

2017 ◽  
Vol 893 ◽  
pp. 132-135
Author(s):  
Zhi Xin Liu ◽  
Wen Song Lin
Keyword(s):  
Contact Angle ◽  
Transition Temperature ◽  
Interfacial Reaction ◽  
Sessile Drop ◽  
Mg Alloys ◽  
Wetting Behavior ◽  
Mg Addition ◽  
Mg Content ◽  
Al Mg Alloys

The wetting behavior of SiC by molten Al and Al-Mg alloys using the sessile-drop testing equipment was investigated. The results showed that Mg has a remarkable influence on the wettability and reaction in the Al/SiC system. The contact angle between SiC substrate and molten Al-Mg alloys decreased more quickly with increasing of Mg content. The transition temperature from non-wetting to wetting dropped with increasing of Mg content, suggesting that the addition of Mg does promote the wettability of SiC by molten Al. The role of the Mg addition on the wetting was presumably attributed to its deoxidation as well as the inhibition of the interfacial reaction between Al and SiC.

scholarly journals Al-Mg alloys.

1988 ◽  
Vol 38 (8) ◽  
pp. 496-512 ◽  
Author(s):  
Hideo YOSHIDA ◽  
Toshiyasu FUKUI
Keyword(s):  
Mg Alloys ◽  
Al Mg Alloys
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