EBSD Characterization of Dendrite Growth Directions, Texture and Misorientations in Hot-Dipped Al - Zn - Si Coatings
EBSD Characterization of Dendrite Growth Directions, Texture and Misorientations in Hot-Dipped Al - Zn - Si Coatings
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DOI：
10.1016/s1359-6454(00)00322-0
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发表时间：
2001-02
期刊：
影响因子：
9.4
通讯作者：
A. Sémoroz;Y. Durandet;M. Rappaz
中科院分区：
文献类型：
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作者：
A. Sémoroz;Y. Durandet;M. Rappaz
用电子背散射衍射仪(EBSD)和光学显微镜对热浸镀Al-Zn-Si(55%Al-43.4%Zn-1.6%Si)涂层进行了分析。在这20个μm-Tick薄膜中，树枝晶的主要生长方向被明确地确定为最接近<；320>；方向。当表面精确地对应于晶粒的(001)面时，面心立方金属通常的四个<；100>；生长方向被平行于涂层生长的八个<；320>；方向(八重对称树枝状图案)所取代。当表面几乎对应于(101)或(111)面时，靠近<；320>；投影的六个生长方向导致了六重对称的树枝状图案。这种形态变化归因于界面能各向异性的内在修正。另一方面，单个颗粒内的晶体取向显示出很大的变化：在非常大的颗粒中，取向偏差高达35度。已经得到了证明。这些错误取向在空间上与涂层中的位置和树枝状图案相关，可根据与特定微观偏析图案相关联的系统晶格间距变化来解释。然而，由于涂层和基材之间的差异热收缩而导致的冷却时产生的热应力也可能导致这些方向错误。结果表明，冷轧基材的强烈织构与Al-Zn-Si涂层的无规取向没有关系。
Al–Zn–Si coatings (55% Al–43.4% Zn–1.6% Si in weight pct) deposited on steel substrates by the hot-dipping process have been analyzed by Electron Back-Scattered Diffraction (EBSD) and optical microscopy. In these 20μm-tick films, the main growth directions of the dendrites have been unambiguously identified as being the closest to <320> directions. When the surface precisely corresponds to a (001) plane of the grain, the four usual <100> growth directions of fcc metals are replaced by eight <320> directions growing parallel to the coating (eight-fold symmetry dendritic pattern). When the surface nearly corresponds to (101) or (111) planes, six growth directions close to <320> projections result in a six-fold symmetry dendritic pattern. This morphology change is attributed to an intrinsic modification of the interfacial energy anisotropy. On the other hand, crystallographic orientation within a single grain is shown to vary substantially: in very large grains, misorientations as large as 35deg. have been evidenced. Being spatially correlated to the location in the coating and to the dendritic pattern, these misorientations are explained in terms of systematic lattice spacing variations associated with the specific microsegregation pattern. However, thermal stresses induced upon cooling as a result of differential thermal contraction between the coating and substrate, can also contribute to these misorientations. Finally, it is shown that there is no relationship between the strongly marked texture of the cold-rolled substrate and the random orientation of the grains of the Al–Zn–Si coating.