Based on elastic theory and yield strength formula of polycrystalline films, the strain-energy densities in differently oriented grains have been calculated for a bcc-polycrystalline film on a substrate. The results show that, (1) prior to yielding, the Fe and Ta are basically similar and with (100), (510), (410) and (511) oriented grains having the lowest strain-energy densities. For Cr, Mo, Nb and V, however, the four lowest strain-energy densities correspond to the grains with (111), (332), (322) and (211) planes oriented parallel to the film surface. For isotropic W, the strain energy density is independent of the grain orientation. (2) In all of yielded bcc-polycrystalline films, the four lowest strain energy densities correspond to the grains with (100), (111), (110) and (411) planes oriented parallel to the film surface. Considering strain energy minimization, we predicate that the grains with these orientations should be favorable in crystal growth successively.
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