Grain Boundary Engineered Lead Alloys

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Abstract
The present work reports oii the effect of grain boundary structure on intergranular corrosion and creep by grain boundary diffusion in polycrystalline lead (Pb). “Special” boundaries characterized by low-Σ misorientations in the Coincident Site Lattice (CSL) model have been shown to exhibit resistance to grain boundary sliding and corrosion. PbCa and PbCaSn alloys having “special” grain boundary frequencies greater than 50% showed a 30 fold reduction in steady-state creep compared with corresponding as-received alloys containing 10% to 28% of low-Σ CSL boundaries in the microstructure of comparable grain size. At the same time, increasing the frequency of “special” boundaries enhanced alloy ductility with no compromize in tensile strength. Results from electrochemical corrosion tests on polarizied Pb alloys immersed in H2SO4 (S.G.=1.28) at 70°C indicate a clear correlation between the frequency of “special” boundaries and the prolifíeration of intergranular corrosion resulting in bulk weight loss from grain-dropping. Collectively, these results advocate adopting a “gram boundary design” approach in developing advanced lead-acid battery electrodes.