Microstructure
Fig. 5 shows typical microstructures of the castings.
Micro-shrinkage was found in the third, fourth and
fifth casting generations, being especially noticeable
after the fifth casting. The grain size has grown
steadily with recasting. A subgrain structure was
found most noticeably after the fifth cast.
The results of the elemental mapping of the
surface by EPMA are shown in Table 3 for gold as
area rates. The gold decreased in fourth and fifth
casts, the change being especially clear after the
fifth cast. The Ag, Pd, Cu and Zn contents did not
change with recasting.