Activation Mechanism and Infiltration Kinetic for Pressureless Melt Infiltration of Ti Activated Al2O3 Preforms by High Melting Alloy

The infiltration mechanism of X3CrNi13‐4 in titanium activated porous alumina preforms has been studied. Investigations revealed isolated steel‐covered titanium particles beyond the infiltration front. The only transport path possible for the steel to form such wetted islands is through the gas phase. Supersaturation due to the mixing of the steel gas phase with the titanium rich gas phase over the activator particle surfaces is proposed as condensation mechanism. Progressive condensation leads to the formation of a melt network, which serves as pathway for the original steel melt to infiltrate the preforms and to fill the remaining pore space in the non‐wetting X3CrNi13‐4/Ti‐Al2O3 sytem.