【作者】 郭朋；

【导师】 兰晔峰；

【作者基本信息】 兰州理工大学 ， 材料学， 2005， 硕士

【摘要】 本文主要是针对现行普遍应用的铝晶粒细化剂在细化时存在缺陷（细化剂中的第二相粒子易产生聚集、沉淀;细化效果随时间延长的抗衰减性差;因Zr、Cr中毒）现象,在Al-Ti-B研制的基础上添加稀土元素,制备新一代的铝合金晶粒细化剂。希望能够改善细化剂的性能,从而研制出一种细化效果好、有长效性、成本低的细化剂。 在实验中主要探讨了加料次序、熔体过热温度、静置温度、搅拌等工艺参数对Al-Ti-B-Re中间合金中各种元素吸收率的影响,对Al-Ti-B-Re中间合金组织中第二相形态、尺寸、分布及细化效果的影响;稀土元素对细化剂抗衰减性的影响,对细化剂重熔性能和重熔后细化性能的影响。 通过金相分析,扫描电镜（SEM）分析,X射线衍射（XRD）分析,电子探针（EPMA）分析和成分分析（ICP）等检测手段,结果表明:混合加料的方式更有利于各种元素的吸收,细化剂也能取得更好的组织形态;采用中低温熔炼（820℃左右）有利于细化剂性能的提高;熔体搅拌、熔体过热温度及静置温度对Al-Ti-B-Re中间合金中TiAl₃、TiB₂及AlTiRe相的形态、尺寸及分布产生较大影响。 在纯铝的细化实验,细化剂的重熔实验和重熔后细化能力变化的实验中,我们得出这样的结论:Al-Ti-B-Re中间合金在Ti的添加量（质量百分含量）为0.01%,细化接触温度为750℃时,细化效果最好时晶粒尺寸为60.2μm,随保温时间延长细化效果将变得下降,但在保温时间达到50分钟时仍有很好的细化效果;Al-Ti-B-Re中间合金细化在经不同温度重熔和多次重熔后仍有较好的细化能力。 通过电子探针分析及已有晶粒细化理论对Al-Ti-B中间合金的细化机理进行了初步探讨。更多还原

【Abstract】 The article contrapose the phenomenon that the refiner used widely has the lacuna when it refines the pure aluminum （The second phases aggregate and deposit easily in the refiner; With time becoming long the declining capability of the refining effect is increased; Poisoning because the Zr、 Cr）, On the basis of research of Al-Ti-B we add the rear-earth and prepare the new kinds of refiner. We hope to improve the capability of the refiner and prepare the refiner that has batter refining effect、 longer refining effect 、lower cost.During the course of experimentation the order of charging、the superheating temperature of aluminum melt、the temperature of holding、stirring and etc will be researched, who will affect the absorptivity of the elements in the master alloy Al-Ti-B-Re, and who will affect the shape、size and the distribution of the second phase; It will also be researched that the effect of the rear-earth to the declining of refiner、to the remelting property and to the refining property.Some experimental methods is used, such as metallographic examination、analyse by scanning electron microscope 、analyse by X-ray、 analyse by electron probe microanalyzer and analyse by IGP. The results show that mixed addition is in favor of absorption of elements, and the refiner can has better microstructure; Casting of middle and low temperature（about 820°C） is in favor of improving property of the refiner; The stirring、the superheating temperature of aluminum melt and the temperature of holding will bring effect to the master alloy Al-Ti-B-Re, such as the shape of phase TiAl₃、 TiB₂、 AlTiRe, the size and distribution.During the experiment of refining、remelting of the refiner and the refining after remelting, the results can be educed that: Although with the time becoming long the grain refining property becomes badly（ the additional quantity of the Ti is 0.01%, the contacting temperature is 750"C）, the best result is that the size of the grain is 60.2 μ m, and grain refining property however is better, and the master alloy Al-Ti-B-Re has better refining property after it was remelted by different temperature and several times.The grain refining mechanism of Al-Ti-B master alloy was discussed elementarily by analyse about nucleus of pure aluminum and the existing theories.更多还原