Formation of drop-shaped inclusions based on Pt, Pd, Au, Ag, Bi, Sb, Te, As during crystallization of the intermediate solid solution in the Cu-Fe-Ni-S system

The phase and chemical composition of drop-shaped inclusions in directionally crystallized intermediate solid solution was studied. The initial melt contained (in mol.%): Fe 31,79; Cu 15,94; Ni 1,70; S 50,20; Sn 0,05; As 0,04; Pt, Pd, Rh, Ru, Ag, Au, Se, Te, Bi, Sb 0,03. Experimental data indicate the simultaneous crystallization of two types of liquids upon cooling of the initial sulfide melt. One of them is formed in the subsystem (Pd, Au, Ag)-(Bi, Sb, Te), and the second - in the subsystem Cu-(S, Bi, Sb, Te). When these liquids solidified, inclusions formed, which we divided into four classes. Class I has a eutectic-like structure with a matrix of Pd(Bi,Sb)xTe1_-x solid solution and Au crystallites with Ag, Cu, and Pd impurities. Class II is formed from sulfosalts with inclusions of Bi and Au. Class III includes inclusions of sperrylite Pt(As,S)₂. Class IV forms compound inclusions from fragments of classes I-III. The experiment described in the work showed a more complex behavior of noble metals and metalloid impurities during the crystallization of complex sulfide-metalloid melts compared with the previously described data of isothermal experiments.