The　effects　of　orientation　and　lamellar　spacing　on　the　interface　microstructure　and　corrosion　behavior　of　a　directionally　solidified　(DS)　Fe-B　alloy　in　a　hot-dip　galvanization　bath　were　investigated.　The　results　indicated　that　the　microstructure　of　the　DS　Fe-B　alloy　consisted　of　oriented　alpha-Fe　and　Fe2B　grains.　The　oriented　Fe2B　with　[002]　preferred　growth　orientation　displayed　low-angle　grain　boundaries　on　the　Fe2B　(001)　basal　plane.　The　DS　Fe-B　alloy　with　Fe2B　vertical　to　the　corrosion　interface　possessed　the　best　corrosion　resistance　to　liquid　zinc　owing　to　the　formation　of　an　interface-pinning　multilayer　induced　by　the　Fe2B　orientation.　The　epitaxially　grown　columnar　zeta-FeZn13　products　were　controlled　by　the　geometric　constraint　of　Fe2B　grain　orientation　and　size,　and　a　mechanism　model　that　explains　the　interfacial　orientation-pinning　behavior　is　discussed　in　detail.　Transmission　electron　microscopy　(TEM)　results　revealed　that　the　possible　orientation　relationships　of　the　oriented　Fe2B　and　columnar　zeta-FeZn13　products　are　(001)(Fe2B)//(-402)(zeta-Fezn13)　and　[002](Fe2B)//[110](zeta-Fezn13).　The　corrosion　damage　of　the　DS　Fe-B　alloy　with　Fe2B　[002]　orientation　vertical　to　the　corrosion　interface　in　liquid　zinc　was　governed　by　the　competitive　mechanisms　of　Fe2B/FeB　transformation　and　microcrack-spallation　resistance,　which　is　proposed　as　being　the　result　of　a　multiphase　synergistic　effect　in　the　micro-structures.　(C)　2016　Acta　Materialia　Inc.　Published　by　Elsevier　Ltd.　All　rights　reserved.