Dendrites [ niobium silicide based alloy ] - ONERA's Science Pictures... Dendritic and eutectic microstructure in a Nb-Si alloy (Nb is the light phase, Nb3Si is the dark phase).... Eutectic microstructure in a niobium silicide based alloy (Nb is the light phase, Nb3Si is the dark phase).... Eutectic microstructure in a niobium silicide based alloy (Nb is the light phase, Nb3Si is the dark phase) ; parts of dendrites are also present....