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Defects of Al-Ni joints caused by Kirkendall-Frenkel effect

Garbala K., Patejuk A.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 1 spec.

455--458

EN

In this paper Kirkendall-Frenkel effects occurring in bimetallic Al-Ni couples has been subjected detailed analysis. The aim of this work was to conduct the model research describing the mechanism of connection zone formation at the aluminum-nickel contact. Al-Ni samples were annealed at temperatures below the melting point of aluminum for a specified periods of time. In the sample annealed at 640 °C for 48 hours Frenkel porosity occurrence has been observed. Maximum pore surfaces share in this area is 35±40%. Diffusion influences in this case can be divided into three zones differing values of component elements concentrations. Microhardness test of these zones reviled that the greatest hardness hasAl3Ni2 equal to 1533HV0,1.

2

Defects in Al casting alloy in contact with Ni coat - as the Frenkla effect

Grabala K., Patejuk A.

Archives of Foundry Engineering

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2007

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Vol. 7, iss. 2

7-10

EN

The subjects of analysis of this work are the defects occurring in the contact area of aluminium and nickel. The purpose of this work was to do a model research. The research concerns the mechanism of the occurrence of the defects in the area of contact: aluminium alloy - nickel coat. The model research describes the making of joints between the above mentioned metals in the warming temperature lower than the time of melting temperature of aluminium and the time of welding. It was affirmed that these defects appear as the result of special diffusion - presented in professional literature as the Kirkendall - Frenkla. The made analysis of results allowed to define parameters and factors of pores - appearing it defined plane shifting in the line of parting between the metals. Appearing of three zones of diffusive alloy was observed in the contact area of given (examined) metals. Observed phenomenon of the Frenkl porosity appeared in the area of the occurrence of the Al3Ni and Al3Ni + Al phases.

3

On the behaviour of Kirkendall markers in solid-state interdiffusion

Paul A., Van Dal M. J. H., Kodentsov A. A., Van Loo F. J. J.

Archives of Metallurgy and Materials

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2004

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Vol. 49, iss. 2

259-276

EN

The migration of inert markers as a result of unequal mobilities of the components during solid-state interdiffusion in a binary system can be rationalized using a Kirkendall velocity construction. It is demonstrated that in a diffusion-controlled interaction the Kirkendall plane, identified by inert particles (markers) placed at the original contact surface of a reaction couple, need not be unique. Multiple planes can develop, but, on the other hand, markers at the original interface sometimes can get dispersed into a diffuse zone on both sides of the contact surface and no unique location of the Kirkendall planes can be defined. It is also shown that the location of the Kirkendall plane(s) inside the diffusion zone can be identified by grain morphology changes within the microstructure of the reaction products. A physico-chemical approach is developed which elucidates the role of the Kirkendall effect in the morphogenesis of interdiffusion systems. The occurrence of one or more Kirkendall planes, characterized by morphology changes in the reaction layers, turns out to be related to different nucleation sites of the product grains.

PL

opis ruchu markerów w procesie dyfuzji wzajemnej w ciele stałym, będący wynikiem różnych ruchliwości poszczególnych składników, można zracjonalizować używając graficznej konstrukcji prędkości Kirkendalla. Zostanie pokazane, że położenie plaszczyzny Kirkendalla, identyfikowanej przez obojetne cząstki umieszczone w miejscu poczatkowej płaszczyzny kontaktu w parze dyfuzyjnej, nie musi być jednoznaczne. oprócz tego, ze możliwych jest kilka płaszczyzn Kirkendalla, to z drugiej strony, markery polożone w chwili poczatkowej w miejscu poczatkowej płaszczyzny kontaktu mogą ulegać rozproszeniu po jej obu stronach i w tej sytuacji nie moąna jednoznacznie zdefiniować jej polożenia. Zostanie także pokazane, że położenie płaszczyzny Kirkendalla w strefie dyfuzji wzajemnej mozna okreslić na podstawie zmian morfologii ziaren i mikrostruktury produktu reakcji. Przedstawiono próbę wyjasnienia wpływu efektu Kirkendalla na morfogenezę dyfuzji wzajemnej. pokazano, że wystepowanie jednej lub kilku płaszczyzn Kirkendalla zwiazane ze zmianą morfologii w warstwach reakcji może wynikać z różnych miejsc zarodkowania ziaren produkcji reakcji.