高强铅基合金组织与性能研究

【作者】 鲁俐；

【导师】 孙勇；

【作者基本信息】 昆明理工大学 ， 材料学， 2009， 硕士

【摘要】 核能利用显示一个国家综合实力,是国防力量和国民经济水平的重要标志,因此和平开发核能为各国所广泛重视。目前,由于对核辐射剂量的控制越发严格,使得屏蔽材料市场竞争日趋激烈,日益受到研究者们的高度重视。各国均投入大量的人力和物力对辐射屏蔽材料进行深入研究,发达国家特别是美国、日本、俄罗斯等国已经形成规模化的屏蔽材料产业,能生产多类别和系列的规格化产品。由于重金属铅对X射线等的卓越吸收能力,以其为基体的屏蔽材料历来广受关注。但铅强度、抗剪切性等力学性能较低而使应用受限,因此开发兼具优良射线屏蔽性和强度性能的铅基材料十分重要。然而,目前国内外高强铅基屏蔽材料的研制报告不多。本课题组在长期研究工作积累的基础上,跳出传统金属材料增强的技术模式,试制出Pb-B-X化合物核屏蔽材料。本文基于对铅基屏蔽材料国内外研究、应用现状的合理调查,并进行文献综述,提出了添加金属Al、Ce以改进Pb-B-X合金力学性能和耐腐蚀性能的思路,制备Pb-B-X-Al、Pb-B-X-Al-Ce核屏蔽材料,以期提高铅基核屏蔽材料的强度性能。同时探讨了相关的力学性能和耐蚀性能。利用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)等分析手段对样品微观结构进行分析,采用拉伸试验,硬度试验,断口分析测试合金的力学性能,采用溶液腐蚀、盐雾腐蚀试验检测材料抗蚀性能,取得了积极研究成果,为后续研究和远景实用化奠定了基础。实验结果表明,铸态Pb-B-X-Al材料微观结构随铝含量的增加产生显著变化,使得合金在凝固过程中先析出的(富X相+富Pb相)共晶组织由片层状演变成骨架状、板条状、最后退化成块状。与此同时,铝的加入,获得了细密、弥散的另一共晶组织。使得Pb-B-X-Al合金的布氏硬度可达到168N/mm2,是传统铅及铅合金的40倍左右,抗拉强度达到328MPa。同时耐蚀性也有所提高。Ce的加入对合金组织也有影响。在合金中加入Ce后将优先形成针状Al4Ce,同时使基体组织变细。稀土Ce的添加阻滞了Pb-B-X-Al合金的阳极反应过程。因此加入Ce可进一步使合金的耐腐蚀性得到提高,当Ce添加量达到0.8wt.%时,则耐蚀性增大不大。论文的结果说明：综合考虑合金的力学性能和耐腐蚀性能,当铝添加量为15wt.%,Ce添加量为0.8wt.%时,合金具有较高的强度、硬度、同时具有一定的耐蚀性和塑性。更多还原

【Abstract】 The use of nuclear energy which shows a country’s comprehensive national strength is an important indicator of national economic levels and national defence, so many countyies have paid close attention to the pesceful development of nuclear energy. At present, as a result of more strict control of nuclear rediation dose, the shielding materials market become more competitive, more and more researchers having attached great importance to it. Many countries have invested a tremendous amount of manpower and material resources to conduct in-depth studies of radiation shielding materials. The developed countries, especially the United States, Japan and Russia, have formed large-scale shielding materials industries and can produce a variety of types and rang of standardized products. As a result of heavy metal lead’s excellent X-ray absorption capacity, shielding materials which uses lead as basic raw material have always been widespread concerned. However, lead’s low mechanical properties such as strength, shearing resistance limit its application, so the development of lead-based materials which have both ray shielding property and strength is very important.However, the current domestic and foreign high-strength lead-based shielding materials much of the development of the report. Based on long-term accumulation of research, this research group was out of the traditional technology enhanced model and prepared Pb-B-X compound nuclear shielding materials. Based on research of the lead-based shielding materials, application of a reasonable investigation and literature review, proposed adding metal Al, Ce in Pb-B-X alloys to improve mechanical properties and corrosion resistance. Pb-B-X-Al, Pb-B-X-Al-Ce alloys were prepared in order to improve mechanical properties and corrosion resistance of lead-based nuclear shielding material. At the same time to explore the relevant mechanical properties and corrosion resistance. To analyse microstructure of the samples by the use of scanning electron microscope(SEM), energy dispersive spectrometer(EDS), X-ray diffractometer(XRD). Used tensile testing, hardness testing, fracture analysis to test mechanical properties of alloys. The corrosion resistance of alloys was tested by corrosion test in solution and salt spray corrosion test, and achieved positive results, and lay the foundation for follow-up study and long-term practial application.Experimental results showed that the as cast Pb-B-X-Al microstructure with the increase of aluminum content have a significant changes. In solidifying process, the first precipitation (X-rich phase+Pb-rich phase) eutectic structue evolved from lamellar stucture into skeleton-like, lath, and finally into massive stucture. At the same time, the addition of aluminum to obtain another eutectic structure which is fine and disperse. It makes Pb-B-X-Al alloys Brinell hardness can be achieved 168N/mm2, it is about 40 times than the conventional lead alloys. The tensile strength of Pb-B-X-Al alloys reached 328MPa. At the same time also increased the corrosion resistance.The addition of Ce also have an impact on the alloys.Ce in the alloys will reacted with Al and generated needle-like Al4Ce compound, at the same time thinning the matrix stuctrue. The addition of rare earth Ce block the Pb-BX-Al alloy anode reaction process.So corrosion resistance of alloys with the Ce can be further improved, when the Ce add up to 0.8wt.%, the corrosion resistance is not increased.The results of papers descripted that considering the mechanical properties of alloys and corrosion resistance, when the aluminum its adding 15wt.%, Ce its adding 0.8wt.%, the alloys with higher strength, hardness, at the same time has some corrosion resistance and plasticity.更多还原