AL SOLUBILITY IN M(6)X COMPOUNDS IN THE TI-CU-O SYSTEM

M(6)X-type compounds in the Ti-Cu-O system, Ti3Cu3O and Ti4Cu2O, have been identified as reaction products at Al2O3/Ag-Cu-Ti braze alloy int erfaces. These compounds which form as a result of the brazing process usually have other elements in solution, the most predominant being A l released from reduction of Al2O3. Microprobe analysis and X-ray diff raction show that the M(6)X structure accommodates a maximum of 15 at% Al, corresponding to a stoichiometry of Ti3Cu2AlO. The compositions T i(3)Cu(A)lO and Ti3Cu3O belong to the same phase field, whereas Ti4Cu2 O has an independent phase field with a marginal (1.5 at%) solubility of Al. The Al atoms occupy Wyckoff position c in the Fd3m M(6)X struct ure.