Abstract
In our investigation of the AgCu25Zn20Cd20 alloy, cadmium was partly or fully replaced by indium due to its toxicity. The influence of this substitution on the fraction, morphology and the distribution of the identified phases has been examined, and the indium distribution in the single phases was established. Melting intervals of several alloys have been determined and their hardness in the cast or in heat-treated state was measured. By means of X-ray diffraction (XRD) phase analysis the intermetallic phase of δ-CuIn has been already established in the alloy with 5 wt.% In. The hardness of the cast alloys was strongly increased and the technological procedures of their manufacture was reduced in the presence of that phase. With higher fraction of indium in the alloy the quantity of the ternary eutectic (α_Ag+ α_Cu+ α-AgCd) in the microstructure was decreasing, and the quantity of ternary mixed crystals α_Ag increased up to 60 vol.%, while the quantity of α_Cu remained fixed. By substitution of indium for cadmium, the melting point decrease to 586 °C and a smaller solidification interval in the alloy of AgCu25Cd15Zn20In5 have been observed.

Key words
soldering, silver solders, intermetallic compounds, phase diagrams, precious metals, indium

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