低铍Cu-0.2Be-XCo合金热处理工艺及组织性能研究

发布时间：2018-01-20 13:49

  本文关键词： Cu-0.2Be-XCo合金 热处理 性能 析出相　出处：《河南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：作为典型的时效强化型铜合金,铍青铜经固溶时效处理后可获得高的强度/硬度、优良的导电/导热性、较好的耐磨抗蚀性等,广泛应用于航空航天、电子电气、日用五金等诸多领域。目前,国内外大量研究和应用的主要是Be含量为1.6%~2.1%的高铍铜合金,然而由于Be及其化合物毒性较大,且制备加工过程对人体和环境有害,要求尽量降低合金中Be的含量,但Be含量降低会致使合金力学性能显著降低。因此如何通过微合金化手段和热处理工艺调控,在最大限度降低Be含量的基础上,开发具有优良综合性能的低铍铜合金具有重要意义。本文在二元低铍Cu-0.2Be合金的基础上,通过添加不同含量(0%、0.5%、1.0%)Co元素形成的Cu-0.2Be-XCo合金,研究了Co元素对合金铸态、挤压态、时效态组织与性能的影响,并获得试验范围内Co元素的较佳添加量为0.5%。以Cu-0.2Be-0.5Co合金为研究对象,考察了时效温度和时间对合金导电率及显微硬度的影响,揭示了时效过程中析出相的形貌、尺寸、分布等特征参量的演变规律,探索了析出相体积分数、导电率及时效时间三者内在关联。为进一步提高合金力学性能,在固溶时效热处理基础上,研究了固溶+冷变形+时效对Cu-0.2Be-0.5Co合金性能与组织的影响,确定了较佳的冷变形时效工艺参数。结果表明:1.随着Co元素含量增加,Cu-0.2Be-XCo合金铸态、挤压态晶粒明显细化,显微硬度提升,导电率下降;经460℃时效后不含Co的Cu-0.2Be合金导电率保持在55.9~59.8%IACS,显微硬度保持在95~100 HV,时效时间在2 h及以上时,Cu-0.2Be-0.5Co合金的综合性能明显优于Cu-0.2Be-1.0Co合金,在试验范围内Co元素的较佳添加量为0.5%。2.Cu-0.2Be-0.5Co合金经950℃×1 h固溶及440~500℃时效后,导电率和显微硬度在时效初期急剧升高,时效中期缓慢增加,时效后期趋于稳定;在460℃×2 h时效条件下合金析出相为椭球状Be12Co,并弥散分布于铜基体,导电率及显微硬度分别为57.1%IACS和243 HV;根据Cu-0.2Be-0.5Co合金在440~500℃时效过程中导电率随时效时间的变化趋势,构建了合金的相变动力学方程和导电率方程。3.Cu-0.2Be-0.5Co合金经冷压缩后导电率随变形量增加而下降,显微硬度随变形量增加而上升;Cu-0.2Be-0.5Co合金较佳冷形变时效工艺为950℃×1 h固溶+50%冷变形+460℃×2 h时效,在此条件下合金导电率和显微硬度获得良好匹配,其值分别为58.0%IACS和285 HV。
[Abstract]:As a typical aging strengthened copper alloy, beryllium bronze can obtain high strength / hardness, excellent conductivity / thermal conductivity, good wear resistance and corrosion resistance after solid solution aging treatment. It is widely used in aerospace. At present, a large number of research and application at home and abroad are mainly be content of 1.6% of high beryllium copper alloy, but due to the toxicity of be and its compounds. The preparation process is harmful to human body and environment, so it is necessary to reduce the content of be in alloy as far as possible. However, the mechanical properties of the alloy will be significantly reduced when the content of be is reduced. Therefore, how to minimize the content of be by means of microalloying and heat treatment. It is of great significance to develop low beryllium copper alloy with excellent comprehensive properties. In this paper, on the basis of binary low beryllium Cu-0.2Be alloy, 0.5% different content of beryllium is added. The effect of Co on the microstructure and properties of Cu-0.2Be-XCo alloy formed by Co element was studied. The optimum addition amount of Co in the range of test is 0.5. The Cu-0.2Be-0.5Co alloy is taken as the object of study. The effects of aging temperature and time on the conductivity and microhardness of the alloy were investigated. The evolution rules of the morphology, size and distribution of precipitated phase were revealed, and the volume fraction of precipitated phase was explored. In order to further improve the mechanical properties of the alloy, it is based on the solid solution aging heat treatment. The effect of solution cold deformation aging on the properties and microstructure of Cu-0.2Be-0.5Co alloy was studied. The optimum aging process parameters of cold deformation were determined. The results showed that the grain size of Cu-0.2Be-XCo alloy was finer and the microhardness was increased with the increase of Co content in the as-cast state of Cu-0.2Be-XCo alloy. Conductivity decreased; After aging at 460 鈩，

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