2020, Wieser, C., Hügel, W., Martin, S., Freudenberger, J., Leineweber, A.

A current issue in electrical engineering is the enhancement of the quality of solder joints. This is mainly associated with the ongoing electrification of transportation as well as the miniaturization of (power) electronics. For the reliability of solder joints, intermetallic phases in the microstructure of the solder are of great importance. The formation of the intermetallic phases in the Cu-Sn solder system was investigated for different annealing temperatures between 472 K and 623 K using pure Cu as well as Cu-1at.%Ni and Cu-3at.%Ni substrate materials. These are relevant for lead frame materials in electronic components. The Cu and Cu-Ni alloys were in contact to galvanic plated Sn. This work is focused on the unexpected formation of the hexagonal ζ-(Cu,Ni)10Sn3 phase at annealing temperatures of 523–623 K, which is far below the eutectoid decomposition temperature of binary ζ-Cu10Sn3 of about 855 K. By using scanning electron microscopy, energy dispersive X-ray spectroscopy, electron backscatter diffraction and X-ray diffraction the presence of the ζ phase was confirmed and its structural properties were analyzed.

2013, Kennett, D.J., Hajdas, I., Culleton, B.J., Belmecheri, S., Martin, S., Neff, H., Awe, J., Graham, H.V., Freeman, K.H., Newsom, L., Lentz, D.L., Anselmetti, F.S., Robinson, M., Marwan, N., Southon, J., Hodell, D.A., Haug, G.H.

The reasons for the development and collapse of Maya civilization remain controversial and historical events carved on stone monuments throughout this region provide a remarkable source of data about the rise and fall of these complex polities. Use of these records depends on correlating the Maya and European calendars so that they can be compared with climate and environmental datasets. Correlation constants can vary up to 1000 years and remain controversial.Wereport a series of high-resolution AMS14C dates on a wooden lintel collected from the Classic Period city of Tikal bearing Maya calendar dates. The radiocarbon dates were calibrated using a Bayesian statistical model and indicate that the dates were carved on the lintel betweenAD 658-696. This strongly supports the Goodman-Mart?nez-Thompson (GMT) correlation and the hypothesis that climate change played an important role in the development and demise of this complex civilization.