Description
The binary system Cu-Sn is the key system for lead-free soldering, because tin is the main component of most of such solder materials and Cu is the most frequently used contact material. Because of its high importance for other applications, e.g. bronze alloys, it has been investigated first more than 100 years ago. Extensive experimental research has been applied to the Cu-Sn system since that time. Several experimental and calculated phase diagrams have been hitherto published. Also thermochemical data like enthalpy of formation of solid and liquid alloys have been performed repeatedly. However, most of the experimental work dates back to the 50ties or earlier and thus new experiments with improved modern techniques were highly indicated. One main issue in our work was to investigate the high temperature phases beta (W-type) and gamma (BiF3-type) and to check the relationship between them. Several samples with higher Cu-contents were examined using PXRD, SEM-EDX, EPMA, DTA and high temperature PXRD. In the latter experiments the presence of the two-phase-field between the beta- and the gamma-phase could not be confirmed. We measured the enthalpy of formation of solid phases in Cu-Sn by solution calorimetry in liquid tin. The results agree well with most of the literature data. The enthalpy of mixing of liquid alloys was determined by drop calorimetry at 500, 700, 900, 1000, 1100 and 1200 °C. The results show clear temperature dependence, most pronounced at lower temperatures. The enthalpy values have been described by a Redlich-Kister fit and alternatively applying an association model. A liquid associate with the composition Cu3Sn was assumed.| Period | 2011 |
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| Event title | 19. Ulm-Freiberger Kalorimetrietage |
| Event type | Conference |
| Location | Freiberg, GermanyShow on map |