The thermal simulated samples were corroded with 4 %
nitric acid alcohol solution after grinding, polishing, and
the microstructures were observed by optical microscopy
and field emission SEM. The extraction replica samples
were made by speed method for TEM observation. The
size, morphology, and distribution of the second-phase
particles were observed in JEM-2000 transmission electron
microscope. Meanwhile, the 400 lm thin slices were cut
from the center of solder joint connected the thermocouple;
the U3 mm backlash was made after grinding to 80 lm;
then the electrolytic double jet test of samples was carried
out in 5 % perchloric acid ? 95 % ethanol solution, and
the fine microstructures were observed in TEM. The
hardness was measured in Vickers-hardness with 10 kg
load, and then, the average value after multipoint measurement
was obtained.