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High speed wafer scale bulge testing for the determination of thin film mechanical properties Rev. Sci. Instrum. 81, 055111 (2010);

A. SÉ MOROZ, L. STREZOV, and M. RAPPAZ A numerical model, which simulates nucleation and growth of Zn grains, has been developed in order to describe quantitatively the solidification of Zn coatings during the hot-dipping process. The inputs of the model are the nucleation distribution, which has been measured by electron backscattered diffraction (EBSD), and the dendritic growth kinetics, calculated with an analytical model of a parabolic dendrite tip modified to account for the interactions with the coating interfaces. The model predicts the shapes of the grain envelopes as a function of the grain orientation and the texture induced by growth. Three types of grain envelopes have been evidenced, depending on the angle between the c-axis and the normal to the coating plane. Moreover, it has been shown that growth reinforces the already existing {00.1} nucleation texture, in good agreement with experimental data. The model also predicts the cooling curve, including recalescence, and the grain size. Thus, it is used to describe the effects of Pb additions on solidification. In particular, it has been shown that Pb increases the nucleation undercooling and strongly decreases the density of active nuclei, thus resulting in a much larger grain size. A. SÉ MOROZ, formerly Ph.D Student, Institute of Materials, Ecole Polytation. The following grain envelopes can be distinguished. technique Fédérale de Lausanne, is Scientist, Alstom, Brown Strasse, 5400 Baden, Switzerland. L. STREZOV, Leader, is with the Pyrometallurgy Group, BHP Billiton, Minerals Technology, Newcastle Technology Centre, Wallsend, (1) The hexagonal shape corresponds to grains that have NSW2287, Australia. M. RAPPAZ, Professor, is with the Institute of Materitheir basal plane parallel to the coating plane. Their six als, Faculty of Engineering, Ecole Polytechnique Fédérale de Lausanne, primary dendrite arms grow along the ͗10.0͘ directions,

A. SÉ MOROZ, L. STREZOV, and M. RAPPAZThe crystallographic orientation of galvanized coatings (Zn-0.2Al-0.15Sb in wt pct) has been characterized by Electron-Backscattered Diffraction (EBSD) and optical microscopy. While 80 pct of the nucleation spots in the coating give rise to single-crystal Zn grains, it has been found that about 20 pct of them give rise to two or more orientation domains, each having a specific crystallographic orientation. For such "polycrystalline Zn grains," the orientations of the domains are crystallographically related: they have a dense crystallographic direction (͗1010͘, ͗1120͘, or ͗0001͘) in common. Moreover, the crystallographic relationships are similar to those observed in snowflakes and can be partially explained by the concept of a coincidence-site lattice (CSL). The EBSD measurements were also used in order to measure quantitatively the crystallographic texture. In particular, it has been evidenced that the (0001) texture of galvanized coatings is the result of two contributions: (1) the nuclei are preferentially oriented with the basal plane parallel to the coating plane (33 pct of the grains have an angle between the basal plane and the coating plane smaller than 22.5 deg), and (2) the grains having the basal plane parallel to the coating plane grow faster (these grains represent 43 pct of the coating surface). This reinforcement of the texture during growth is in agreement with that predicted by growth models, which take into account the effect of the interfaces.