Lead-Bismuth Eutectic or LBE is a eutectic alloy of lead (44.5 at%) and bismuth (55.5 at%) used as a coolant in some nuclear reactors, and is a proposed coolant for the lead-cooled fast reactor, part of the Generation IV reactor initiative.
It has a melting point of 123.5 °C/254.3 °F (pure lead melts at 327 °C/621 °F, pure bismuth at 271 °C/520 °F) and a boiling point of 1,670 °C/3,038 °F.
Lead-bismuth alloys with between 30% and 75% bismuth all have melting points below 200 °C/392 °F.
Alloys with between 48% and 63% bismuth have melting points below 150 °C/302 °F.
While lead expands slightly on melting and bismuth contracts slightly on melting, LBE has negligible change in volume on melting.