Influence cells segregation on structural hardening mechanisms

of PbCaCdAg alloys for battery’s grids

 

E. Saad1*, A. Balhamri2,3, Az. Mouhsen2, M. Harmouchi2, E.M. Oualim2,4

1Laboratoire Physico-chimie des Procédés et des Matériaux,

Faculté des Sciences et Techniques, Université Hassan 1er, B.P 461 Settat, Morocco.

2Laboratoire Rayonnement & Matière : Equipe d’Optique Appliquée et Transfert d’Energie, Faculté des Sciences et Techniques,  Université Hassan 1er, BP 461 Settat, Morocco.

3Chimie des Interactions Plasma Surface, CIRMAP, UMONS Research Institute for Materials Science and Engineering,

Université de Mons, Place du Parc 20, B-7000 Mons, Belgium.

4Ecole Supérieure de Technologie, Université Hassan 1er, Passage d'Alger B.P 218 Berrechid, Morocco.

* Corresponding author: E-mail: saadelmadani@yahoo.fr

Received: 04 July 2012; revised version accepted: 09 October 2012

Abstract

     The phenomena of aging and overaging of PbCaCdAg alloys are characterized by discontinuous transformation without precipitation and discontinuous lamellar transformation of Pb3Ca, its hardening and softening. The presence of silver make a delay in the kinetics of hardening transformation and a slight increase in hardness. 

     Gradually, as the concentration of silver increases, the kinetics of hardening transformation becomes more and more slowly producing an increase in hardness. In addition, we observe a formation of eutectic mixture zones of Pb-Ag whose the volume increases versus the concentration of silver, these areas have, in the case of high silver content (0.3%), a specific arborescent dendrite formation more marked. We also find that the average silver content (0.15% Ag) allow relatively high hardness. The rehomogenization treatment effect makes a delay in the kinetics process of aging and overaging. This is due to the elimination of segregation cells, reducing processing sites and giving a delay in the kinetics hardening transformation.

 

Keywords: Alloys; Aging; Battery grids; Hardness; Optical microscopy; Silver.

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