發(fā)布時間：2018-12-20 08:39

【摘要】：隨著核工業(yè)技術的發(fā)展,反應堆結構材料將面臨越來越嚴苛的中子輻照條件。中子輻照下,材料內(nèi)部產(chǎn)生大量缺陷,進而造成膨脹、硬化、非晶化和脆化等導致材料的失效。對傳統(tǒng)材料進行結構強化和性能優(yōu)化已難以滿足未來核工業(yè)對材料抗輻照性能的要求,這促進了對新型抗輻照材料的研究。由于在許多方面表現(xiàn)出特殊的性質,近幾十年來納米晶材料一直是科學研究的熱點。納米晶材料最大的結構特征是其細小的晶粒尺寸(納米級)導致其擁有遠多于普通材料的界面和晶界。以往的研究表明,晶界或界面能充當間隙原子及空位的陷阱,因此擁有大量晶界的納米晶材料可能表現(xiàn)出優(yōu)異的抗輻照性能。鋁及合金由于擁有良好的熱、電、力學性能及抗輻照性能而廣泛應用于核工業(yè)。目前,已能通過一些方法制備出高致密度的塊體納米晶Al,其強度和硬度分別可達到粗晶Al的3~16倍和2~11倍。真空熱壓是一種較為有效的納米晶材料制備技術,然而目前還沒有詳細系統(tǒng)的討論真空熱壓制備納米晶Al的報道�；谏鲜銮闆r,本文以自懸浮定向流技術制備的納米Al粉末為原料,采用真空熱壓技術制得了致密的納米晶Al塊體。系統(tǒng)地討論了熱壓溫度和壓力對熱壓納米晶Al的微觀結構和顯微硬度的影響。隨后對納米晶Al進行了不同劑量水平的快中子(E1 Me V)輻照,討論了快中子輻照對納米晶Al微觀結構和顯微硬度的影響。實驗結果表明:熱壓納米晶Al塊體的顯微硬度分布在0.8~1.98 GPa范圍內(nèi),且隨熱壓溫度的升高先增大后減小,隨熱壓壓力的增大出現(xiàn)先快后慢的增長。不同的熱壓溫度和熱壓壓力范圍內(nèi),不同的固結機理主導著納米晶Al的致密化過程。低密度塊體表現(xiàn)出明顯的壓痕尺寸效應,而高密度塊體并沒有表現(xiàn)出這種現(xiàn)象。隨不同的快中子輻照劑量,納米晶Al的平均晶粒尺寸增大了2.09%~9.09%(2.6~11 nm),顯微硬度增大了3.54%~4.37%(62.6~76.9 MPa)。隨著中子劑量的增加,納米晶Al的平均晶粒尺寸和顯微硬度的增長率均表現(xiàn)出增大的趨勢。
[Abstract]:With the development of nuclear technology, reactor structural materials will face more and more stringent neutron irradiation conditions. Under neutron irradiation, a large number of defects occur inside the material, which leads to the failure of the material, such as expansion, hardening, non-crystallization and embrittlement. The structural strengthening and performance optimization of traditional materials have been difficult to meet the requirements of the future nuclear industry for the radiation resistance of materials, which promotes the research of new type of radiation resistant materials. Nanocrystalline materials have been the focus of scientific research in recent decades because of their special properties in many aspects. The biggest structural feature of nanocrystalline materials is that their fine grain size (nanocrystalline size) leads to much more interfaces and grain boundaries than ordinary materials. Previous studies have shown that grain boundaries or interfaces can act as traps for interstitial atoms and vacancies, so nanocrystalline materials with large grain boundaries may exhibit excellent radiation resistance. Aluminum and alloys are widely used in nuclear industry due to their excellent thermal, electrical, mechanical and radiation resistance properties. At present, bulk nanocrystalline Al, with high density can be prepared by some methods. The strength and hardness of the bulk nanocrystalline Al, are 3 ~ 16 times and 2 ~ 11 times of that of coarse Al, respectively. Vacuum hot pressing is an effective preparation technology for nanocrystalline materials. However, there is no detailed report on the preparation of nanocrystalline Al by vacuum hot pressing. Based on the above situation, the dense nanocrystalline Al powders were prepared by vacuum hot pressing from nano-sized Al powders prepared by self-suspension directional flow technique. The effects of hot pressing temperature and pressure on microstructure and microhardness of hot-pressed nanocrystalline Al were systematically discussed. The effects of fast neutron irradiation (E1 Me V) on the microstructure and microhardness of nanocrystalline Al were discussed. The experimental results show that the microhardness distribution of hot-pressed nanocrystalline Al is in the range of 0.8 ~ 1.98 GPa, and increases first and then decreases with the increase of hot pressing temperature, and increases at first and then slowly with the increase of hot pressing pressure. Different consolidation mechanisms dominate the densification process of nanocrystalline Al at different hot pressing temperature and pressure range. The effect of indentation size is obvious in low density blocks, but not in high density blocks. With different doses of fast neutron irradiation, the average grain size of nanocrystalline Al increased by 9.09% (2.611 nm),) and 4.37% (62.6% 76.9 MPa). With the increase of neutron dose, the average grain size and the growth rate of microhardness of nanocrystalline Al show an increasing trend.
【學位授予單位】：西南科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB383.1;O614.31

【共引文獻】

相關期刊論文 前3條

1 Quanwei Zhan;Tao Suo;Cunxian Wang;Kui Xie;Zhongbin Tang;;TEMPERATURE SENSITIVITY AND PREDICTION OF THE MECHANICAL BEHAVIORS OF ULTRAFINE GRAINED ALUMINUM UNDER UNIAXIAL COMPRESSION[J];Acta Mechanica Solida Sinica;2014年04期

2 宋言紅;李裕;易勇;羅江山;楊蒙生;李愷;雷海樂;;熱壓納米晶鋁的微觀結構和顯微硬度[J];材料熱處理學報;2014年07期

3 鄭戰(zhàn)光;謝昌吉;孫騰;袁帥;;一種超細晶材料的混合硬化模型及其數(shù)值模擬[J];機械工程學報;2014年20期

相關博士學位論文 前8條

1 翟月雯;P91合金鋼晶粒演化特征研究與厚壁管熱擠壓工藝數(shù)值模擬[D];機械科學研究總院;2013年

2 何慶;航空發(fā)動機機匣包容性機理及數(shù)值仿真方法研究[D];浙江大學;2012年

3 許春萍;體心立方鐵中晶界對氦團簇形成的影響[D];蘭州大學;2014年

4 閆濤;55SiMnMo中空鋼孔型軋制及冷卻過程數(shù)值模擬與試驗研究[D];燕山大學;2014年

5 王曉峰;超臨界機組用耐熱鋼的開發(fā)及相關基礎研究[D];中南大學;2013年

6 李超;Ti-55511合金的熱變形行為及晶粒細化研究[D];中南大學;2013年

7 余敏;非均質材料中位錯與不同尺度典型缺陷的多場耦合干涉[D];湖南大學;2014年

8 姜慶偉;超細晶純金屬材料塑性變形與損傷行為的溫度效應[D];東北大學;2011年

相關碩士學位論文 前6條

1 龔旭;鋁銅合金形變與退火過程中微觀組織與力學性能研究[D];重慶大學;2013年

2 段忠;超細晶材料在高應變率加載下絕熱剪切的形成及傳播規(guī)律[D];寧波大學;2012年

3 齊躍;ECAP制備的工業(yè)純鐵及純鋁的高溫變形行為研究[D];東北大學;2013年

4 趙彥杰;玻碳材料脈沖電沉積納米晶體鎳及其合金的性能研究[D];燕山大學;2014年

5 張松林;Sm-Fe-N納米薄片的制備、結構及其磁性能研究[D];昆明理工大學;2014年

6 謝昌吉;超細晶材料的本構建模及其力學行為的研究[D];廣西大學;2014年

，

本文編號：2387735