THE SYSTEM PD-FE-NI-S AT 900 AND 725-DEGREES-C

The system Pd-Fe-Ni-S was studied at 900 and 725 degrees C by means of dry condensed charges. At both temperatures it is dominated by the ph ase relationships involving sulphide melt. Pd-Fe-Ni alloys with broad miscibility primarily coexist with the melt; they are relatively enric hed in Pd, whereas the associated melt is enriched in Ni. With decreas ing temperature the melt recedes from Fe-rich regions. The incompatibi lity of PdS (extensive solid solution with Ni) and mss at 900 degrees C is replaced by their co-crystallization (+/- disulphide(s) of Ni,Fe or +/- sulphide melt) at 725 degrees C. The Ni/Fe ratio in the melt ch anges regularly against that in mss with increasing S fugacity and Pd contents in these two phases. (Ni,Fe)(3+/-x)S-2 and Pd4S play importan t roles at 725 degrees C. The data offer an array of distribution coef ficients and solubility values suitable for geological interpretations .