【作者】 张舟永；

【导师】 凌国平；

【作者基本信息】 浙江大学 ， 材料加工工程， 2010， 硕士

【摘要】 氚在大多数金属材料中具有强的渗透性,为了减少乃至阻止氚的渗透,又不牺牲结构材料的整体性质,最合适的方法是在材料表面加上一薄层氚扩散系数低的物质,作为氚渗透阻挡层（TPB）。目前世界上开展核聚变研究的国家均认为比较可行的方案是在堆用金属结构材料表面形成阻氚涂层。通过富铝涂层氧化制备α-Al₂O₃膜,因其具有自修复性能,是众多研究机构的主要研究方向。但α-Al2O3一般需要950℃以上温度才能形成。因此,如何在750℃以下温度得到α-Al2O3膜成为关键。本文以Cr合金化降低Al2O3相转变温度为技术路线,探讨用Al-Cr急冷合金薄带在不锈钢表面制备富铝涂层的可能性。为此,首先对急冷Al-Cr合金薄带的组织结构进行研究,考察了热处理参数与Al-Cr急冷合金薄带组织转变之间的关系,研究粗糙度、温度、时间等对Al-Cr急冷合金薄带低温氧化行为的影响,最后,探讨Al-Cr急冷合金薄带与不锈钢基体的接触反应行为。得到了以下结论:在急冷合金带组织结构研究中,发现急冷合金薄带被分为两类,含或不含A145Cr7析出相。其中Cr含量为2wt%,6wt%,8wt%的急冷合金由单一固溶体组成;而Cr含量为10wt%,15wt%,18wt%的急冷由固溶体与析出相组成。在急冷合金薄带热处理研究中,发现:高于350℃温度时,低Cr含量合金可析出细小颗粒,随着热处理温度升高、时间延长,颗粒尺寸变大,但温度高于Al的熔点660℃以上时,会导致颗粒异常长大。此外,颗粒尺寸存在临界值,达到临界值后,延长热处理时间,析出相颗粒尺寸变化不大。与模铸合金相比,析出相颗粒尺寸细小,且均匀分布。在急冷合金带热氧化研究中,通过透射电镜衍射花样及EDS分析证明,Al-Cr急冷合金薄带在大气中,低于750℃下氧化可以得到α-Al2O3。通过热处理调节急冷合金的组织,并粗化表面,能够促进合金低温氧化时形成α-Al2O3。在Al-Cr急冷合金薄带直接在不锈钢表面制备富铝涂层的尝试中,发现Cr含量低于8wt%的Al-Cr急冷合金薄带能够与不锈钢发生接触反应,形成含Al、Cr合金的涂层;而10 wt%及以上Cr含量的急冷合金薄带因表面存在大量的A145Cr7析出相,与基体不发生接触反应。更多还原

【Abstract】 Tritium has a strong permeability in mostly of metal materials; In order to reduce or prevent the penetration of tritium, and without sacrificing the structure of the materials, the most appropriate approach is to add a thin layer that is low tritium diffusion, as a tritium permeation barrier (TPB). Currently the research around the world shows that the more viable solution is forming a coating on the surface of metal structural material for TPB.Because of its self-healing properties,α-Al2O3 film could be prepared by Al-rich coating. However,α-Al2O3 generally is formed above 950℃. Therefore, it is critical how to get a-A12O3 film below 750℃. In this paper, the way to reduce Al2O3 phase transition temperature is Cr alloying, the feasibility of preparation of Al-rich coatings by rapid quenching Al-Cr alloy film with stainless steel surface. For this purpose, first, the organizational structure of quench Al-Cr alloy films, and the relationship between heat treatment parameters with the phase transformation of quench Al-Cr alloy film, that were studied, the influence of roughness, temperature and time on the oxidation behavior of Al-Cr quenching Alloy at low-temperature;Finally, the contact reaction of quenching Al-Cr alloy film and stainless steel substrate was studied. The following conclusions are reached:Quenching alloy film was divided into two categories, with or without A145Cr7 precipitates. In which the quenching alloys of Cr content 2wt%, 6wt%, 8wt% by a single solid solution composition; the quenching alloys of the Cr content of 10wt%, 15wt%, 18wt% are constituted by the solid solution and the precipitation of phase.Low-alloy Cr content can be precipitated small particles, above 350 ’C, with higher temperature and more time, particle size is larger, but when the temperature is higher than Al melting point (660℃),it would result in abnormal particles grown up. In addition, there is threshold of particle size, when particle size reach the threshold, Compared with casting alloys, precipitated phase particle size small, and evenly distributed.The TEM diffraction pattern and EDS analysis showed that, quenching Al-Cr alloy film formα-Al2O3,below 750℃, in the atmosphere. Regulating organization and coarsening surface, can promote alloy formedα-Al2O3 at low-temperature.the quenching Al-Cr alloy film of less than 8wt% Cr content contacting react with stainless steel, formed alloys coating including Al, Cr; however, the quenching Al-Cr alloy film of 10 wt% and higher content of Cr, own a large number of Al45Cr7 precipitates on the surface, then the substrate contact reaction does not occur.更多还原