Fig. 1 Schematic illustration of the sessile drop apparatus

Fig. 2 SEM images of Y2O3 substrates: a, c, e surface images of Y2O3-A, Y2O3-B and Y2O3-C substrates, respectively; b, d, f cross-sectional images of Y2O3-A, Y2O3-B and Y2O3-C substrates

Fig. 3 Images of sessile droplets of molten Ti47Al samples on Y2O3 substrates with different open porosities at 1600 °C

Fig. 4 Variation in contact angle of molten TiAl alloy with time on Y2O3 substrates with different open porosities

Fig. 5 Equilibrium contact angles of molten Ti47Al droplets on Y2O3 substrates with different open porosities

Fig. 6 SEM micrographs of the cross section perpendicular to the interface of the alloy droplets: a Ti47Al/Y2O3-A system; b Ti47Al/Y2O3-B system; c Ti47Al/Y2O3-C system

Fig. 7 Thickness of sand adhesion of the TiAl droplets resting on different open porosities Y2O3 substrates

Fig. 8 Map analysis of Ti,Al,Y, and O elements of the interface of the solidified alloy droplets: a Ti47Al/Y2O3-A system; b Ti47Al/Y2O3-B system; c Ti47Al/Y2O3-C system

Fig. 9 Backscattered electron images of the matrix of alloy droplets for a Ti47Al/Y2O3-A system; b Ti47Al/Y2O3-B system; c Ti47Al/Y2O3-C system

Fig. 10 Volume fraction of Y2O3 particles in alloy droplets on Y2O3 substrates with different open porosities

Fig. 11 Schematic configurations of sessile drops resting on the substrates with different open porosities

Fig. 12 Surface roughness and contact angle versus open porosity of Y2O3 substrates

Fig. 13 Typical 3D surface morphology of the porous ceramic substrate