Quantification of the Mg2Si β″ and β′ phases in AlMgSi alloys by transmission electron microscopy
Quantification of the Mg2Si β″ and β′ phases in AlMgSi alloys by transmission electron microscopy
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DOI：
10.1007/bf02670664
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发表时间：
1995-08
期刊：
影响因子：
--
通讯作者：
S. Andersen
中科院分区：
文献类型：
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作者：
S. Andersen
开发了一种使用透射电子显微镜 (TEM) 测定 6xxx 铝合金中 Mg2Si β" 和 β' 相密度的方法。对析出物结构具有不同粗度的 AlMgSi 合金的时效硬化挤压型材进行了检查。通过暗场 (DF) 成像，在 <100> 观察方向上排列的 β” 针形成对比。使用点污染法确定厚度在 10 pct 以内。在随后的校正之后，沉淀物的数量密度然后可以被量化，通常在5 pct之内。正如预期的那样，β”沉淀物的平均数密度与材料的拉伸强度密切相关。通过类似的方法获得β'的密度。由于不考虑无沉淀物区域，因此密度代表最大值。拉伸强度对β′和β″的数密度之比非常敏感。通过确定平均 β'' 或 β' 针的体积，可以确定相应的相的体积分数。这些相的量化可能有利于涉及此类合金机械性能的计算。
A method has been developed to determine the density of the Mg2Si β″ and β′ phases in 6xxx aluminum alloys using transmission electron microscopy (TEM). Age-hardened extruded profiles of an AlMgSi alloy, having different coarseness in the precipitate structure, were examined. By darkfield (DF) imaging, β″ needles aligned in a <100> viewing direction were brought into contrast. Thickness was determined within 10 pct using a spot contamination method. After subsequent corrections, the number density of precipitates could then be quantified, usually within 5 pct. As expected, the average number density of the β″ precipitates correlates well with the material’s tensile strength. A density of β ′ was obtained by a similar method. The densities represent maximum values since precipitate-free areas are not considered. Tensile strength is quite sensitive to theratiobetween the number densities of β′ and β″. By determining the volume of an average β″ or β′ needle, corresponding volume fractions of the phases can be determined. Quantification of these phases could benefit calculations involving mechanical properties of such alloys.