首页> 外文OA文献 >Experimental and numerical study of microstructure formation and the origin of crystallographic misorientation in Al-Zn-Si alloy coatings
【2h】

Experimental and numerical study of microstructure formation and the origin of crystallographic misorientation in Al-Zn-Si alloy coatings

机译:Al-Zn-Si合金镀层的微观结构形成与晶体学取向错误的起源的实验与数值研究

代理获取
本网站仅为用户提供外文OA文献查询和代理获取服务,本网站没有原文。下单后我们将采用程序或人工为您竭诚获取高质量的原文,但由于OA文献来源多样且变更频繁,仍可能出现获取不到、文献不完整或与标题不符等情况,如果获取不到我们将提供退款服务。请知悉。

摘要

Al-Zn-Si alloy coatings are widely used for the corrosion protection of steel sheets. In addition to the favorable corrosion properties, the Al-43wt%Zn-1.6wt%Si coatings present several features which are of metallurgical interest. The first one is their surface appearance dominated by the typical spangle morphology exhibiting dull and shiny areas on the coating surface. Further on, the dendrite tips do apparently not grow along the 〈100〉 crystallographic directions that are typical for fcc-metals, but rather along directions in between 〈100〉 and 〈110〉. In addition, continuous variations of the crystallographic orientation, up to 35°, are observed within individual grains of Al-Zn-Si coatings [Sémoroz1 01]. The objective of the present study is to establish a better understanding of the microstructure development which is responsible for the formation of both the characteristic spangle pattern and the important variations of crystallographic orientation within the grains. In order to elucidate these questions, the present study includes three main axes, (i) a detailed microstructure characterization of industrially solidified samples, (ii) modeling work which encompasses microstructure modeling by the phase field method and a geometrical model, as well as the determination of the solid-liquid interfacial energy anisotropy by an inverse method, and (iii) re-solidification experiments aimed at studying the behavior of Al-Zn-Si layers under modified solidification conditions. The results show that the dendrite network spreads quickly in the coating layer at a temperature between 530 to 535°C. During growth, the dendrite tips are separated from the confining boundaries by a thin, solute-rich liquid film. It was found that the preferred dendrite growth directions are in between 〈100〉 and 〈110〉, 28.5° from 〈100〉. Further on, a mathematical expression for the interfacial energy anisotropy of the considered alloy has been determined. The combination of the geometrical model and surface topography measurements allowed concluding that the spangle pattern is due to preferential dendrite growth along one of the two boundaries confining the melt layer. In addition, the new experimental evidence forced to discard the mechanisms previously proposed for the formation of intragranular crystallographic misorientations. The experimental findings acquired during this study indicate that the solidification shrinkage occurring in the area of the grain envelope is the driving force for the formation of the observed intragranular misorientations. The solidification shrinkage leads to the development of tensile stresses in the oxide film covering the coating while it solidifies. These stresses apply on the dendrite network and lead to plastic deformation in the tip area of the growing dendrite arms.
机译:Al-Zn-Si合金涂层被广泛用于钢板的腐蚀防护。除有利的腐蚀性能外,Al-43wt%Zn-1.6wt%Si涂层还具有冶金学上的几个特征。第一个是它们的表面外观,该表面外观由典型的亮晶状形态主导,在涂层表面显示出暗淡和发亮的区域。此外,枝晶尖端显然不会沿fcc金属典型的〈100〉结晶方向生长,而是沿〈100〉至〈110〉之间的方向生长。此外,在Al-Zn-Si涂层的各个晶粒中观察到高达35°的晶体取向连续变化[Sémoroz1.0]。本研究的目的是建立对微观结构发展的更好的理解,微观结构的发展既负责形成特征性的亮晶石图案,又负责晶粒内晶体学取向的重要变化。为了阐明这些问题,本研究包括三个主要方面,(i)工业凝固样品的详细微观结构表征,(ii)建模工作,其中包括通过相场法和几何模型进行的微观结构建模,以及通过逆方法确定固液界面能各向异性,以及(iii)重新凝固实验,旨在研究在修改的凝固条件下Al-Zn-Si层的行为。结果表明,在530-535℃之间的温度下,枝晶网络在涂层中迅速扩散。在生长过程中,枝晶尖端被一层薄的富含溶质的液膜与边界隔开。发现优选的枝晶生长方向在directions100〉和〈110〉之间,从〈100〉开始为28.5°。此外,已经确定了所考虑合金的界面能各向异性的数学表达式。几何模型和表面形貌测量结果的结合可以得出结论,亮晶形图案是由于沿限制熔体层的两个边界之一优先生长枝晶。另外,新的实验证据迫使放弃先前提出的用于形成晶内晶体学取向错误的机制。在这项研究中获得的实验结果表明,在晶粒包壳区域发生的凝固收缩是形成观察到的晶粒内取向错误的驱动力。固化收缩导致在固化时覆盖涂层的氧化膜中产生张应力。这些应力作用在枝晶网络上,并导致正在生长的枝晶臂尖端区域发生塑性变形。

著录项

  • 作者

    Niederberger Christoph;

  • 作者单位
  • 年度 2007
  • 总页数
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类

相似文献

  • 外文文献
  • 中文文献
  • 专利

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号