Transformation characteristics of Al–Ag and Al–Ag–Ti alloys

El-Khalek, A.M. Abd

doi:10.1016/j.jallcom.2007.05.055

Cited by 13 publications

(4 citation statements)

References 18 publications

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“…The yield stress s y and the fracture stress s f , are determined as has been mentioned in the previous investigation. 14 The temperature dependence of s f , s y and the fracture time t f of the test samples is shown in Fig. 6.…”

Section: Resultsmentioning

confidence: 99%

Influence of heat treatment on stress–strain behaviour and lattice parameters of Sn–In alloy

Al-Ganainy

El-Khalek

Sakr

2011

Materials Science and Technology

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Sn based alloys have important industrial applications specially as pewters and soldering materials. One of these alloys, Sn–5·2 wt-In alloy, is designed to be examined in the present work. The differential thermal analysis of this alloy gives a melting temperature value of 493 K. An empirical equation that can be used to determine the melting temperature of some Sn–In alloys is derived. Two different heat treated groups of samples, slowly cooled and quenched, are prepared. The phases present in these two groups of samples are determined from their X-ray diffraction patterns. The isothermal tensile stress–strain tests of all samples are reported at temperatures between 343 and 403 K. The changes of the work hardening parameters and also of the lattice parameters of the β-Sn phase with the deformation temperature are discussed. The values of the activation energy characterise a dislocation fracture mechanism.

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Section: Resultsmentioning

confidence: 99%

Influence of heat treatment on stress–strain behaviour and lattice parameters of Sn–In alloy

Al-Ganainy

El-Khalek

Sakr

2011

Materials Science and Technology

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“…A conventional tensile testing machine similar to that explained previously 16 was employed. The stress acting on the sample was gradually increased (with 30 s internal between two successive loadings), and the elongation was recorded with an accuracy of 10 25 m, immediately after applying the stress.…”

Section: Methodsmentioning

confidence: 99%

Effect of phase transformation and indium addition on workhardening characteristics of Al–Zn alloy

El-Khalek¹

2012

Materials Science and Technology

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Tensile characteristics of both Al–10Zn and Al–10Zn–0·2In (wt-%) alloys were investigated in the temperature range from 413 to 473 K. The workhardening coefficient, the yield stress, the fracture stress, resilience, toughness and fracture time generally decrease with increasing deformation temperature. On the other hand, the fracture strain and dislocation slip distance increased with increasing deformation temperature. The two observed temperature regions around the transformation temperature (443 K), which characterise the magnitude of variation of these parameters point to two fracture mechanisms activated with 23·2 and 49·4 kJ mol−1 for the low and high temperature regions respectively. Indium addition caused general increase for all the measured strength parameters. The microstructures of the samples under investigation have been examined after stress–strain deformation by X-ray diffraction analysis.

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“…Al-Ag supersaturated solid solution evolves towards the equilibrium state following the sequence [1][2][3][4]: Supersaturated solid solution → Guinier-Preston (GP) zones → metastable γ' phase → equilibrium γ phase. The Guinier-Preston zones (GP), consisting of silver atom clusters, are coherent with the matrix.…”

Section: Introductionmentioning

confidence: 99%

INFLUENCE OF TRACES ADDITION OF TIN ON THE GROWTH AND ON THE COARSENING OF THE GUINIER-PRESTON ZONES IN Al-10% at.Ag ALLOY

Lourdjane

Hanifi

Raho

2017

Acta Metall Slovaca

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The formation of the Guinier-Preston zones in aluminium alloys is closely linked with the excess vacancies. Traces of tin added to an Al-Ag alloy exert an influence on the Guinier-Preston zones precipitation. Due to their high binding energy with vacancies, tin atoms trap some of these available to promote the diffusion of silver atoms for the formation of the Guinier-Preston zones. At 125°C, tin microalloying slows down the reaction of the Guinier-Preston zones precipitation. The diffusion coefficient of the solute atoms in the Sn free alloy and in the Sn added alloy are determined during the coarsening regime which obeys to the Lifshitz, Slyosov and Wagner theory.Keywords: Guinier-Preston zones; precipitation; coarsening; diffusion; vacancies; hardening 1 Introduction Al-Ag supersaturated solid solution evolves towards the equilibrium state following the sequence [1-4]: Supersaturated solid solution → Guinier-Preston (GP) zones → metastable γ' phase → equilibrium γ phase. The Guinier-Preston zones (GP), consisting of silver atom clusters, are coherent with the matrix. The metastable phase γ'(Ag2Al) is semi-coherent with the matrix and the equilibrium phase γ(Ag2Al), is incoherent with the matrix. Precipitation starts from the formation of GP zones, which are isomorphous with the matrix and, therefore, have a lower interfacial energy than intermediate or equilibrium precipitate phases that possess a distinct crystal structure. As a result, the nucleation barrier for GP zones is significantly smaller. The effect of microalloying elements on the behaviour of age-hardenable alloys such as Al-Ag is an interesting physical problem addressing the mechanisms of transport and aggregation of the solute. Trace elements have been found to exert a disproportionate influence on the structure and properties of Al alloys compared with the amounts added which may be less than 0,1 molar fraction . Most trace element effects arise because they modify the nucleation and the growth characteristics of the phases which form during precipitation [5][6][7][8][9]. It is well known that the formation of the GP zones in aluminium alloys is closely linked with the excess vacancies. A number of models of GP zones precipitation assisted by vacancies has been developed by several authors [10][11][12]. GP zones formation is governed by a transport mechanism of solute atoms by solute atom-vacancy complexes. The high binding energy between tin atoms and vacancies leads to the formation of vacancy-tin atom pairs and silver atom-vacancy-tin atom complexes.

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Transformation characteristics of Al–Ag and Al–Ag–Ti alloys

Cited by 13 publications

References 18 publications

Influence of heat treatment on stress–strain behaviour and lattice parameters of Sn–In alloy

Influence of heat treatment on stress–strain behaviour and lattice parameters of Sn–In alloy

Effect of phase transformation and indium addition on workhardening characteristics of Al–Zn alloy

INFLUENCE OF TRACES ADDITION OF TIN ON THE GROWTH AND ON THE COARSENING OF THE GUINIER-PRESTON ZONES IN Al-10% at.Ag ALLOY

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