鎢的表面納米化及鎢、碳化硅氦離子注入研究
發(fā)布時間：2018-11-05 15:47
【摘要】：面向等離子體材料及部件(PFM/PFCs)不僅是實現(xiàn)受控核聚變反應(yīng)的關(guān)鍵材料,也是亟待解決的“瓶頸”問題。鎢以其高熔點、熱導(dǎo)性好、高溫強度高、不與氚共沉積等優(yōu)點已被選作核聚變反應(yīng)堆ITER及DEMO的第一壁面向等離子體材料,且偏濾器部分將采用全W作高熱負(fù)荷材料。但鎢極高的韌脆轉(zhuǎn)變溫度、輻照腫脹、氦脆等缺點一直是制約其應(yīng)用的主要原因。因此提高鎢及鎢合金的機(jī)械性能,降低其韌脆轉(zhuǎn)變溫度對實現(xiàn)鎢在核聚變反應(yīng)堆中的應(yīng)用具有重要的科學(xué)意義和實用價值；同時研究氦泡的形核、長大、遷移過程,確定氦泡在鎢中存在形態(tài),對評價輻照引起鎢機(jī)械性能的降低(輻照硬化、輻照脆化、熱導(dǎo)降低等)具有重要的意義。本文首次采用表面機(jī)械研磨處理方法(SMAT)對純鎢(W)及氧化鑭鎢(W-1%wt La2O3, WL10)進(jìn)行表面自納米化處理,使表面發(fā)生劇烈的塑性變形,在W及WL10表面均形成了厚度約11μm的納米層,外表層晶粒的平均尺寸約11nm。經(jīng)φ1.5mm ZrO2彈丸處理后的W,其最大三點抗彎強度可達(dá)1851.0MPa,對應(yīng)的DBTT值較未處理前大約下降50℃；對WL10而言,其三點抗彎強度較未處理的WL10下降了120MPa,但對應(yīng)的DBTT值較未處理前大約下降200℃。TEM研究結(jié)果表明表面納米層存在大量的層錯及位錯胞,W的納米化機(jī)理與典型的具有高層錯能的bcc金屬一致。第四章中,通過SRIM軟件模擬聚變堆中的面向等離子體材料遭受到較低能量(～keV)、高濃度的氦離子對鎢的輻照損傷行為；首次通過實驗在電鏡下觀察到了固體氦泡,固態(tài)氦泡具有bcc結(jié)構(gòu),晶體常數(shù)為0.447nm,氦泡與基體W的位向關(guān)系為(110)He//(002)w,該位向關(guān)系與文獻(xiàn)報道的第一性原理計算結(jié)果完全一致,在此基礎(chǔ)上,對固態(tài)氦泡的形成機(jī)理進(jìn)行了討論。第五章中比較了低原子序數(shù)SiC與高純石墨SMF-800作為面向等離子體材料及部件的可行性。研究了不同溫度、不同劑量條件下將氦離子同時注入SiC和石墨中對二者表面形貌的影響,及所形成的氦泡尺寸及密度,結(jié)果表明SiC抗氦離子輻照損傷性能明顯優(yōu)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，
本文編號：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，
本文編號：2312533
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