Hardening process in ternary lead-antimony-tin alloys for battery grids

It is known that lead-antimony alloys are very well hardened by continuous precipitation, whereas lead-tin alloys present a discontinuous precipitation with a weak hardening effect. In these binary alloys, there is precipitation of either antimony or tin. In ternary alloys, the compound SbSn can also precipitate. This study is focused on the type of precipitation, the nature and the morphology of the precipitated phases, and the intensity of hardening in ternary Pb---Sb---Sn alloys in relation to the composition of the alloys and the ternary diagram. To simulate the different processes of grid production, four states are studied, namely, as-cast product, rehomogenized, cold worked, cold worked and rehomogenized. The alloys contain up to 2.5 wt.% Sb and 2.5 wt.% Sn.