“…There are some measurements of Young's modulus using compression tests [56] and micro-and nano-indentation [49], but since none of these phases is isotropic, we need measurements of the full stiffness tensor. Ab initio calculations have been performed [57,58,59,60,61] for Cu 3 Sn and Cu 6 Sn 5 , however there is a large spread on the reported data and it is difficult to conclude on which values are most accurate. Therefore, we have performed extra ab initio calculations for the 4 phases, with convergence criteria that are more severe than in any of the previous studies, to guide our selection of appropriate stiffness coefficients for the phase-field simulations.…”