[Effects of gold on age-hardening in Ag-25 wt. % Pd-7 wt. % Cu alloys (author's transl)].

Effects of third elements (0, 1, 2, 4, 6, 8 and 12 wt. % Au) on the age-hardening in Ag-25 wt. % Pd-7 wt. % Cu alloys were studied by means of electrical resitivity, micro-hardness measurement, optical microscopy observation and X-ray diffraction. The results are summarized as follows. (1) The temperature range of an initial increase in resistivity was lowered with increasing concentration of gold. (2) The age-hardening process was retarded by the addition of gold. (3) Changes in X-ray diffraction patterns which was aged at lower temperature range exhibited that continuous precipitation process. On the other hand, changes in diffraction patterns aged at higher temperature range showed discontinuous precipitation process. (4) The lattice parameters of alpha phase and alpha2 phase (Ag-rich) were found to decrease with increase in gold content, while the lattice parameter of PdCu type superlattice was found to increase with increase in gold. (5) The nature of the interface between precipitates and the matrix was discussed on the basis of the changes in lattice parameter obtained.