Fig. (3) Wettability of the vertical sapphire plate by Ni-40.5at.%Nb melt at 1250 °C: (A) the initial plate immersion, advancing contact angle θ_adv.1, 1- alumina crucible, 2- melt; (C) the plate extraction, receding contact angle θ_rec.1, H- length of the extracted plate; (C) the second plate immersion H₁<H, advancing contact angle θ_adv.2.