ISOTHERMAL SECTIONS OF PHASE-EQUILIBRIA IN THE AL-ALCO-ALNI SYSTEM

The phase equilibria of the ternary Al-AlCo-AlNi system are demonstrat ed using isothermal sections at 1170, 1100, 1050, 900, 850, 730, End 6 00 degrees C. These are based on metallographic and TEM investigations and on several temperature-concentration sections, which are investig ated using thermal analyses. The Scheil reaction scheme is used for ex planation of the data. Eleven phases from the binaries Al-Co and AI-Ni and the three ternary phases Y-2 (Co2NiAl9), X and D were found at ro om temperature. The binary high-temperature phase Co4Al13(h) is stabil ized in the ternary down to room temperature by Ni addition (YI). The phase field of D is composed of several modifications which can hardly be distinguished by light microscopy. These modifications are not con sidered in the present paper. 45 three-phase regions can be derived fr om the reaction scheme in the Al-AlCo-AlNi subsystem.