钨的表面纳米化及钨、碳化硅氦离子注入研究
发布时间：2018-11-05 15:47
【摘要】：面向等离子体材料及部件(PFM/PFCs)不仅是实现受控核聚变反应的关键材料,也是亟待解决的“瓶颈”问题。钨以其高熔点、热导性好、高温强度高、不与氚共沉积等优点已被选作核聚变反应堆ITER及DEMO的第一壁面向等离子体材料,且偏滤器部分将采用全W作高热负荷材料。但钨极高的韧脆转变温度、辐照肿胀、氦脆等缺点一直是制约其应用的主要原因。因此提高钨及钨合金的机械性能,降低其韧脆转变温度对实现钨在核聚变反应堆中的应用具有重要的科学意义和实用价值；同时研究氦泡的形核、长大、迁移过程,确定氦泡在钨中存在形态,对评价辐照引起钨机械性能的降低(辐照硬化、辐照脆化、热导降低等)具有重要的意义。本文首次采用表面机械研磨处理方法(SMAT)对纯钨(W)及氧化镧钨(W-1%wt La2O3, WL10)进行表面自纳米化处理,使表面发生剧烈的塑性变形,在W及WL10表面均形成了厚度约11μm的纳米层,外表层晶粒的平均尺寸约11nm。经φ1.5mm ZrO2弹丸处理后的W,其最大三点抗弯强度可达1851.0MPa,对应的DBTT值较未处理前大约下降50℃；对WL10而言,其三点抗弯强度较未处理的WL10下降了120MPa,但对应的DBTT值较未处理前大约下降200℃。TEM研究结果表明表面纳米层存在大量的层错及位错胞,W的纳米化机理与典型的具有高层错能的bcc金属一致。第四章中,通过SRIM软件模拟聚变堆中的面向等离子体材料遭受到较低能量(～keV)、高浓度的氦离子对钨的辐照损伤行为；首次通过实验在电镜下观察到了固体氦泡,固态氦泡具有bcc结构,晶体常数为0.447nm,氦泡与基体W的位向关系为(110)He//(002)w,该位向关系与文献报道的第一性原理计算结果完全一致,在此基础上,对固态氦泡的形成机理进行了讨论。第五章中比较了低原子序数SiC与高纯石墨SMF-800作为面向等离子体材料及部件的可行性。研究了不同温度、不同剂量条件下将氦离子同时注入SiC和石墨中对二者表面形貌的影响,及所形成的氦泡尺寸及密度,结果表明SiC抗氦离子辐照损伤性能明显优于SMF-800石墨。
[Abstract]:Plasma-oriented materials and components (PFM/PFCs) are not only the key materials to realize the controlled nuclear fusion reaction, but also the bottleneck problem to be solved. Tungsten has been selected as plasma-oriented material in the first wall of ITER and DEMO for its advantages of high melting point, good thermal conductivity, high temperature strength and no co-deposition with tritium, and the full W material will be used as high heat load material in the filter part. However, the shortcomings of high ductile transition temperature, irradiation swelling and helium brittleness are the main reasons restricting its application. Therefore, it is of great scientific significance and practical value to improve the mechanical properties of tungsten and tungsten alloys and to reduce the ductile and brittle transition temperature for the application of tungsten in nuclear fusion reactor. At the same time, the nucleation, growth and migration of helium bubble are studied, and the existence of helium bubble in tungsten is determined, which is of great significance in evaluating the reduction of mechanical properties (irradiation hardening, irradiation embrittlement, thermal conductivity reduction, etc.) caused by irradiation. In this paper, the surface self-nanocrystalline treatment of pure tungsten (W) and lanthanum tungsten oxide (W-1%wt La2O3, WL10) was carried out by surface mechanical grinding method (SMAT) for the first time, resulting in severe plastic deformation on the surface. Nanocrystalline layers with a thickness of about 11 渭 m were formed on both W and WL10 surfaces, and the average grain size of the outer layer was about 11 nm. When treated with 蠁 1.5mm ZrO2 projectile, the maximum three-point bending strength can reach 1851. 0 MPA, and the corresponding DBTT value is about 50 鈩，
本文编号：2312533
[Abstract]:Plasma-oriented materials and components (PFM/PFCs) are not only the key materials to realize the controlled nuclear fusion reaction, but also the bottleneck problem to be solved. Tungsten has been selected as plasma-oriented material in the first wall of ITER and DEMO for its advantages of high melting point, good thermal conductivity, high temperature strength and no co-deposition with tritium, and the full W material will be used as high heat load material in the filter part. However, the shortcomings of high ductile transition temperature, irradiation swelling and helium brittleness are the main reasons restricting its application. Therefore, it is of great scientific significance and practical value to improve the mechanical properties of tungsten and tungsten alloys and to reduce the ductile and brittle transition temperature for the application of tungsten in nuclear fusion reactor. At the same time, the nucleation, growth and migration of helium bubble are studied, and the existence of helium bubble in tungsten is determined, which is of great significance in evaluating the reduction of mechanical properties (irradiation hardening, irradiation embrittlement, thermal conductivity reduction, etc.) caused by irradiation. In this paper, the surface self-nanocrystalline treatment of pure tungsten (W) and lanthanum tungsten oxide (W-1%wt La2O3, WL10) was carried out by surface mechanical grinding method (SMAT) for the first time, resulting in severe plastic deformation on the surface. Nanocrystalline layers with a thickness of about 11 渭 m were formed on both W and WL10 surfaces, and the average grain size of the outer layer was about 11 nm. When treated with 蠁 1.5mm ZrO2 projectile, the maximum three-point bending strength can reach 1851. 0 MPA, and the corresponding DBTT value is about 50 鈩，
本文编号：2312533
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