Rare-Earth Metals (REMs) in Nickel Aluminide-Based Alloys: I. Physicochemical Laws of Interaction in the Ni-Al-REM and Ni_xAl_y-REM-AE (Alloying Element) Systems

摘要

The data on the Ni-Al-R (R = REM Sc, Y, La, lanthanides) binary and ternary systems and the interactions of three rare-earth metals (yttrium, lanthanum, cerium) with the main alloying elements (Ti (Zr, Hf), Cr (Mo, W) that are introduced into Ni_3Al-based VKNA alloys are analyzed. The binary aluminides of REMs in the Ni-Al-R ternary systems are shown to be in equilibrium with neither NiAl nor Ni_3Al. The solid solution of aluminum in i?Ni_5, which penetrates deep into these ternary systems, is the most stable phase in equilibrium with Ni_3Al. In the NiAl (Ni_3Al)-AE-R systems, REM precipitation (segregation) on various defects and interfaces in nickel aluminides is likely to be the most probable, and REMs are thought to interact with the most active impurities in real alloys (C, O, N), since REMs have a large atomic radius and, thus, are virtually undis-solved in nickel, aluminum, and nickel aluminides.