Cu-Cr-Zr和Cu-Zn-Cr-Zr合金时效特性研究

【作者】 张生龙；

【导师】 尹志民；

【作者基本信息】 中南大学 ， 材料物理与化学， 2002， 硕士

【摘要】 采用铸锭冶金法制备了大功率异步牵引电动机转子用导条合金和端环合金，通过硬度测试、室温拉伸、高温拉伸、电导率测定、金相分析、XRD、SEM、TEM等方法研究了不同加工工艺和热处理工艺对上述合金力学性能、导电性能及其组织结构的影响和变化规律，并从理论上进行了分析和解释。研究结果表明： 1．Cu-Zn-Cr-Zr合金是典型的时效强化型合金。在本论文实验条件下，导条合金综合性能较好的加工工艺为挤压—水淬—冷拉—450℃／4h时效，合金的力学和电学性能可达：σb=467MPa,σ0.2=390MPa．δ5=20.8％σr=64.6％IACS；端环合金综合性能较好的加工工艺为热锻—固溶—450℃／4h时效，合金的力学和电学性能可达：σb=388MPa,σ0.2=315MPa．δ5=27.8％，σr=84.65％IACS。 2．研究合金不仅在常温具有很好的强度和导电性，而且具有较高的高温强度，导条合金在350℃时σb仍保持在274MPa左右，σ0.2仍保持在250MPa左右；端环合金在350℃时σb仍保持在200MPa以上，σ0.2仍保持在165MPa以上。 3．研究合金的强化机制包括固溶强化、加工硬化及析出强化。形变热处理(固溶—冷拉—时效)工艺可大大提高合金时效后的最终强度，时效后形变热处理对电阻率影响很小。冷拉后的合金时效过程中受到析出和再结晶过程交互作用的影响。析出的第二相粒子不仅强化了基体而且一定程度上抑制了再结晶的进行，从而使合金的硬度进一步提高。 4．冷变形—时效过程中影响合金电导率变化的主要因素有回复—再结晶过程、过饱和固溶体的分解和析出，回复和再结晶使合金的电导率提高，过饱和固溶体的分解使得基体固溶度显著降低同时也使电导率显著升高。 5．合金高导电性的根本原因在于时效后形成的弥散型复相结构，细小的析出粒子弥散分布于高电导率的基体之中，对电导率的影响很小。其导电机制可用单元立方体导电模型来解释。更多还原

【Abstract】 Cu-Zn-Cr-Zr conducting bar alloy and Cu-Cr-Zr end ring alloys used for superpower asynchronous traction motor rotor were prepared by Ingot Metallurgy. Using hardness measurement, tensile test at room and higher temperature, electrical resistance test at room and higher temperature, optical microscopy, XRD, SEM, and TEM, the mechanical and electric properties and the microstructure of above alloys at different treatment were studied. Them were also analysed and explained in theory. The results show that:The first, Cu-Zn-Cr-Zr alloy is a typical aging strengthing alloy; the optimal process of bar alloy is extrusion-quench-cold-drawing-aging(450PC/4h), it’s mechanical and electrical performance can reach o b=467MPa, o 0.2=390MPa, 8 5=20.8%, a r=64.6%IACS; the optimal process of end ring alloy is hot-forging-solution-aging(450癈/4h), it’s mechanical and electrical performance can reach o b=342MPa, o 0a=216MPa. 6 5=27.8%, o r=74.3%IACSoThe second, above alloys not only have good strength and conductibility at room temperature but also have good strength at high temperature. Bar alloy can hold o b=274MPa and o o2=250MPa at 350癈 while end ring alloy can hold o b=200MPa and o 02=l65MPa at350癈.The third, the strengthening mechanisms of above alloys mainly include solution strengthening, strain-strengthening and aging strengthening. Thermomechanical treatment(solution-cold-drawing-aging) can increase alloys’ strength greatly. The alloy in aging after cold-drawing was influenced by the interaction of precipitation and recrystaUization. The precipitates not anly can strengthen the matrix but also can restrain recrystaUization.The fourth, electrical conductivity of alloys was influenced by reversion-recrystaUization and precipitation of supersaturation solid solution. Reversion-recrystaUization can increase electrical conductivity. Precipitation can also increase conductivity by reducing solid solubility in matrix.FinaUy, high-conductivity of aUoys come from disperse and duplex phase structure. It’s conducting mechanism can be explained by cubic conducting unit model.更多还原