High-Temperature Wettability and Interactions between Y-Containing Ni-Based Alloys and Various Oxide Ceramics

To obtain appropriate crucible materials for vacuum induction melting of MCrAlY alloys, four different oxide ceramics, including MgO, Y(2)O(3), Al(2)O(3), and ZrO(2), with various microstructures were designed and characterized. The high-temperature wettability and interactions between Ni-20Co-20Cr-10Al-1.5Y alloys and oxide ceramics were studied by sessile drop experiments under vacuum. The results showed that all the systems exhibited non-wetting behavior. The contact angles were stable during the melting process of alloys and the equilibrium contact angles were 140° (MgO), 148° (Y(2)O(3)), 154° (Al(2)O(3)), and 157° (ZrO(2)), respectively. The interfacial reaction between the ceramic substrates and alloys occurred at high temperature. Though the ceramics had different microstructures, similar continuous Y(2)O(3) reaction layer with thicknesses of about 25 μm at the alloy-ceramic interface in MgO, Al(2)O(3), and ZrO(2) systems formed. The average area percentage of oxides in the alloy matrices were 0.59% (MgO), 0.11% (Al(2)O(3)), 0.09% (ZrO(2)), and 0.02% (Y(2)O(3)), respectively. The alloys, after reacting with MgO ceramic, had the highest inclusion content, while those with the lowest content were in the Y(2)O(3) system. Y(2)O(3) ceramic was the most beneficial for vacuum induction melting of high-purity Y-containing Ni-based alloys.