Search for metallic glasses at eutectic compositions in the Ag-Cu-Ge,Ag-Cu-Sb and Ag-Cu-Sb-Ge systems

Phase relationships have been examined in several slowly cooled ternary Ag-Cu-Ge, Ag-Cu-Sb, and quaternary Ag-Cu-Ge-Sb alloys, by means of optical and electron metallography, including electron microprobe. The obtained results have been used to locate the compositions of eutectic points, and also to establish the related details of the surfaces of primary crystallization. The composition regions likely to yield metallic glasses were explored by rapid melt quenching using the spinning wheel technique. Amorphous ribbons were obtained from alloys in the region of the lowest melting eutectic in the Ag-Cu-Ge system, but not in the Ag-Cu-Sb and Ag-Cu-Ge-Sb systems. However, metallic glass was produced in two Ag-Cu-Sb alloys with compositions along a pseudobinary eutectic line at an electron concentration ofe/a = 1.8. This is the same value as that associated with metallic glass formation at the ternary eutectic composition in the Ag-Cu-Ge system. All obtained metallic glasses were found to have relatively low crystallization temperatures in the range between 140 and 170 °C.