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Aluminium and oxygen tracer diffusion in polycrystalline alpha-Al2O3

铝和氧示踪剂在多晶 α-Al2O3 中的扩散

基本信息

批准号：
237775578
负责人：
Dr. Peter Fielitz
金额：
--
依托单位：
Institut für Metallurgie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2016-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/237775578?language=en
关键词：
Aluminium oxygen tracer diffusion polycrystalline

项目摘要

Alpha-Al2O3 is an important refractory material which has numerous technical applications: as an in situ growing self-healing oxide scale, as a massive material and as reinforcement fibres in composites. This means that polycrystalline microstructures are of prime importance in the technological use of alpha-Al2O3. It is therefore extremely disadvantageous that to date only very few data on directly measured oxygen grain boundary diffusivities exist and that there is no data at all (!) available on aluminium grain boundary diffusion. This lack of data considerably hinders quantitative modelling of diffusion controlled processes in polycrystalline alpha-Al2O3. Therefore, for modelling diffusion controlled processes (creep, sintering, alpha-alumina scale growth on aluminium bearing Fe or Ni base alloys) it is generally conjectured that, in analogy to bulk transport, oxygen grain boundary diffusion is much slower than aluminium grain boundary diffusion. In order to check this conjecture quantitatively, it is absolutely necessary to perform direct tracer diffusion experiments. For the first time ever (!) experimental data on the 26Al grain boundary tracer diffusion in polycrystalline alpha-Al2O3 will be determined in this project. This will allow to quantify the ratio Db-Al/Db-oxy of grain boundary diffusivities which is a key parameter in theoretical studies.Yttrium doping has, from the technological point of view, a very positive effect as it slows down both the creep rate of polycrystalline alpha-Al2O3 and the growth rate of alpha-Al2O3 scales on aluminium bearing Fe or Ni base alloys. In order to demonstrate that yttrium doping affects oxygen grain boundary diffusion two other groups performed 18O tracer diffusion studies whose results are, however, controversial. In order to fully understand the technologically important effect of yttrium doping, it is necessary to supply data for the aluminium grain boundary tracer diffusion in yttrium doped alpha-alumina. Therefore, in this project the aluminum grain boundary diffusion in yttrium doped alpha-alumina will be measured and the controversial oxygen grain boundary diffusion data will be experimentally checked.

α-Al 2 O3是一种重要的耐火材料，具有许多技术应用：作为原位生长的自愈合氧化皮，作为块状材料和作为复合材料中的增强纤维。这意味着多晶微结构在α-Al 2 O 3的技术应用中是最重要的。因此，极其不利的是，迄今为止仅存在非常少的关于直接测量的氧晶界扩散率的数据，并且根本没有数据（！）可用于铝晶界扩散。这种数据的缺乏极大地阻碍了多晶α-Al 2 O 3中扩散控制过程的定量建模。因此，对于扩散控制过程（蠕变、烧结、含铝Fe或Ni基合金上的α-氧化铝尺度生长）的建模，通常需要说明的是，与体传输类似，氧晶界扩散比铝晶界扩散慢得多。为了定量地检验这一猜想，进行直接示踪扩散实验是绝对必要的。有史以来第一次（！）本项目将确定26 Al晶界示踪剂在多晶α-Al 2 O 3中扩散的实验数据。这将允许定量的晶界扩散系数的比率Db-Al/Db-oxy，这是在理论研究中的关键参数。钇掺杂，从技术的角度来看，具有非常积极的效果，因为它减缓了多晶α-Al 2 O3的蠕变速率和α-Al 2 O3的规模在铝轴承Fe或Ni基合金的生长速率。为了证明钇掺杂影响氧晶界扩散，另外两个小组进行了18 O示踪扩散研究，其结果是，然而，有争议的。为了充分理解钇掺杂的重要技术效应，有必要提供钇掺杂α-氧化铝中铝晶界示踪剂扩散的数据。因此，在本项目中，将测量掺钇α-氧化铝中的铝晶界扩散，并对有争议的氧晶界扩散数据进行实验检查。