Interaction mechanism between DD5 superalloy with different Y content and ceramic molds with Y2O3 layer

Abstract

DD5 alloys with different Y content were produced by directional solidification (DS) using ceramic molds with the Y2O3 layer. The interaction mechanisms between the corresponding alloys and the Y2O3 layer were discussed. It was found that the Y2O3 layer effectively hindered the direct contact reaction between the active melt and the Al2O3 ceramics, which was conducive to improving the purity of the melt and reducing the loss of Y. Slight dissolution and decomposition of the Y2O3 layer under high temperature melt erosion resulted in the release of Y and O elements into the alloy. The involvement of Y in the melt changed the interfacial reaction mechanism between the Y2O3 layer and the alloy. The interfacial reaction products of melting the DD5 alloy without Y were Al2Y4O9 and Y2O3, while the interfacial reaction product of melting the DD5 alloy with Y was mainly Y2O3.