STRUCTURAL HARDENING MECHANISM OF LEAD-ST RONTIUM-TIN ALLOYS FOR BATTERYS GRIDS .1. LEAD-STRONTIUM ALLOYS

The equilibration of the oversaturated PbSr alloys is studied by diffe rent experimental methods : optical microscopy, microcalorimetry, hard ness measurements. Several structural states are considered : as-cast alloy, rehomogenised, rolled. The contents of Sr are 0.08 and 0.12 wei ght %. The explored temperatures are 20 and 80 degrees C. The last tem perature corresponds to the curring temperature and to the highest ope rating temperature. The time of heat treatment ranges from one minute to one year. An aging followed by an overaging, both corresponding to a discontinuous transformation mechanism are cleary observed.