【作者】 邹勇志；

【导师】 曾建民；

【作者基本信息】 广西大学 ， 材料物理与化学， 2004， 硕士

【摘要】 高铝锌基合金是近年来在耐磨行业应用日益广泛的一类新型合金。它具有抗拉强度和硬度高，耐磨性好，摩擦温升低，材料成本低廉等优点；同时还具有良好的工艺性能，而且熔化时能耗低无污染，因此引起了许多国家研究人员的关注。 高铝锌基合金的固态转变对其性能有着重要的影响，这一直是高铝锌基研究的重点。并且以往对于高铝锌基合金的研究主要集中于含铝量小于30％的合金，对于含铝量大于30％的合金研究较少且不系统。本文采用了光学金相分析、高温金相分析、扫描电子显微分析、示差扫描热分析和热膨胀性能等实验方法对含铝量大于30％的合金的固态相变与热物理性能进行了系统的研究，观察到固态相变的一些新现象。 由实验结果和分析可得出以下结论： (1)首次利用高温金相显微镜连续地观察共析转变的动态过程。 (2)高铝锌基合金的铸态组织由初生白色α枝晶、包围在α枝晶外缘的β相、枝晶间白亮的ε相和黑色的晶间共晶体组成。 (3)五种合金的共析转变温度基本相同，均在285℃左右，ZA50的共析转变热最小。随着含铝量的增加，共析转变热减小；合金的熔点增加；合金的熔化热也增加，但增幅不大。试验合金的平均熔化热在170 广西大学硕士学位论文高铝锌基合金的相变与热物理性能的研究kJ瓜g左右，高铝锌基合金熔化时能耗低。 (4)随着温度升高，实验合金的热膨胀系数和热容都上升。而随着合金中Al含量的增多，组织中a相数量逐渐增多，其膨胀系数逐渐降低。ZA45在各实验温度下的热膨胀系数是最小的。ZA40在各实验温度下的热容是最大的。 (5)通过对zA30的100“c等温热处理在不同时间的金相组织的观察，推测高铝锌基合金在100”C时效时发生调幅分解和胞状析出。更多还原

【Abstract】 As a new kind of alloy, high Aluminum Zn-based alloys have found wide use in wear-resisting machinery in recent years. Not only does it feature a high tensile strength, high hardness, wear-resisting etc., but it is also characteristic of excellent processing properties and low energy consumption, no pollution in melting as well. Due to all of these advantages, this type of alloy has drawn many attentions of researchers in many countries.Solid transformation of high Aluminum Zn-based alloy has an important influence on its properties; so, the mechnism of the transformation has being investigated by researchers as a key subject. However, most of the researches were focused on alloys with aluminum content lower than 30%. Few researches have dealed with the alloys with aluminum content more than 30%. In the present research, a systematic study on solid transformation and thermophysical properties of alloy with aluminum content higher than 30% has been carried out. By means of metallographic, high temperature metallographic analysis, scanning electron microscope, thermal ananysis and thermal expansion experiment etc., some new phenomena have been observed as for solid transformation of the alloys. The main conclusions are:(1) The dymatic process of eutectoid transformation is observed continuously though high-temperature microscope for the first time.(2) The as-cast microstructure of high Aluminum Zn-based alloy consists of white a phase which takes on dendrite morphology, B phase which appears around a phase,and phase and eutectic.(3) The eutectoid transformation temperature of five alloys is identical , being about 285C. And ZA50’s heat of eutectoid transformation is the lowest. With the increasing of aluminum content, the heat of eutectoid transformation reduces, while the melting point of alloy rises. The average heat of fusion of five testing alloys remains about 170 kJ/kg, so high Aluminum Zn-based alloy consume less energy in their melting.(4) As the temperature rises, the alloy’s coefficient of thermal expansion and heat capacity also go up. With the increasing of Aluminum content, the number of a phase increase, and its coefficient of thermal expansion drops. Under every temperature, the coefficient of thermal expansion of ZA45 turns to be the smallest, and the heat capacity of ZA40 turns to be the biggest.(5) Through continual observations to different microstructure of ZA30 under isothermal heat treatment at the temperature 100C. It seems that spinnodal and celluar transformation have happened during ageing stage.更多还原