Intrinsic thermal fatigue in a mechanically unconstrained Pb-free, Sn-rich Sn–3.8Ag–0.7Cu alloy has been investigated under cyclic thermal loading between 293 K and 353 K. Fatigue damage is shown to occur preferentially along high angle grain boundaries. From a combination of orientation imaging microscopy and finite element modelling it appears that this fatigue damage and stresses resulting from the thermal anisotropy of Sn are highly correlated.
Matin, M. A., Coenen, E. W. C., Vellinga, W. P., & Geers, M. G. D. (2005). Correlation between thermal fatigue and thermal anisotropy in a Pb-free solder alloy. Scripta Materialia, 53(8), 927-932. https://doi.org/10.1016/j.scriptamat.2005.06.034