The system Cu-Fe-Se; reconnaissance phase relations between 500 and 700 degrees C

Phase relations in the system Cu-Fe-Se at 500 degrees C have been studied in silica tubes by quenching experiments whereas the assemblages up to 700 degrees C have been established mainly through DTA runs on presynthesized charges. Synthetic eskebornite reacts on heating to form Se-intermediate solid solution and (Cu,Fe)Se (sub 2-x) , followed by Se-poor solid solution which decomposes into Cu (sub 2-x) Se and gamma -Fe (sub 1-x) Se between 635 and 640 degrees C. Synthetic (Cu,Fe)Se (sub 2-x) on heating shows an endothermic effect at 410 degrees C, a progressive loss of Se between 575 degrees and 655 degrees C and melts to a liquid of similar composition at 660 degrees C. According to the thermal behaviour of the two ternary solid solutions, the variation of phase relations between 500 degrees and 700 degrees C and consistent four-phase equilibria reactions are reported.