【作者】 崔庆玲；

【导师】 王明星；

【作者基本信息】 郑州大学 ， 凝聚态物理， 2009， 硕士

【摘要】 近年来,LSM工艺制备铝基复合材料得到广泛应用,已制备出TiB₂增强相均匀细小（＜1μm）、性能优良的各类铝合金复合材料,但是该方法存在一个较严重的缺陷,即原位生成的TiB₂增强相常被盐膜包覆,造成TiB₂增强相与基体之间界面的污染,削弱了增强效果。此外,该方法还存在原料利用率低、环境污染等问题。与混合盐反应法制备TiB₂/Al复合材料不同,本文提出了一种向电解低钛铝熔体加Al-B中间合金制备含TiB₂颗粒Al合金的新方法,并对这种方法进行了较系统地研究,研究内容主要包括如下几方面:首先,研究了向电解低钛铝熔体加入Al-B中间合金制备含TiB₂颗粒Al合金的可行性,并对反应生成的TiB₂颗粒对材料硬度的影响进行了测试分析。结果表明:这种原位反应法制备工艺是可行的。而且,因在电解低钛铝熔体中,钛主要以原子的形式存在且分布均匀,故原位反应生成的TiB₂粒子颗粒均匀、细小且弥散的分布在熔体中;随含量的增加,TiB₂粒子在铝熔体中的分布仍能保持良好的均匀性,并使Al合金的布氏硬度大幅度提高。其次,研究了熔体温度对TiB₂颗粒生成反应的影响。结果表明:从750℃到950℃,随温度的升高,反应生成的TiB₂粒子偏聚程度减弱,TiB₂粒子的尺寸变小、分布均匀性变好,材料的硬度提高;但是,随熔体温度的升高,脆性相Al₃Ti的生成量增多。Al₃Ti相的生成会降低合金材料的性能。因此,熔体温度不宜过高,850℃为该工艺制得TiB₂/Al合金的最佳熔体温度。第三,研究了过量Ti对TiB₂/Al合金微观组织的影响,结果表明:过量Ti的存在可能有效的细化α-Al基体,使TiB₂颗粒分布均匀性变好,提高TiB₂/Al合金的硬度。第四,研究了Mg对TiB₂/Al合金熔体中TiB₂颗粒团聚的影响。结果表明:Mg元素的加入能有效抑制反应生成TiB₂的团聚,使TiB₂粒子的尺寸变小、分布均匀性变好,提高TiB₂/Al合金的硬度;加入适量的Mg元素,还可改善TiB₂颗粒与铝液界面的润湿性,这对提高材料的力学性能有利。最后,利用电解低钛铝、Al-B中间合金等基于上述工艺制备了具有不同TiB₂含量的TiB₂/Al-Si-Mg合金,研究了在Al-Si-Mg合金熔体中TiB₂粒子的原位反应生成及其对合金的微观组织和力学性能的影响。结果表明:此原位反应法制备含TiB₂粒子应用合金是基本可行的,随TiB₂粒子含量的增加,合金的强度有所下降,但塑性却大幅提高,合金的综合力学性能有所改善。更多还原

【Abstract】 In recent years , LSM technique has extensively been used to prepare aluminum-matrix composites, and many different kinds of aluminum-matrix composites with well-distributed fine TiB₂ particles （<1μm） and good mechanical properties have been produced using this technique. However, there are some defects in the technique. For example, the TiB₂ particles formed are easily wrapped by the salt film, which probably contaminate the interfaces between the TiB₂ particles and aluminum-matrix and impaire the reinforcing effect of the TiB₂ particles. Besides, LSM technique has yet the disadvantages of low utilization ratio of raw materials and polluting environment. In this paper, a new method of in-situ formation of TiB₂ particle by adding Al-B master alloy to electrolytic low-titanium aluminum （ELTA） melt to prepare TiB₂/Al alloy has been put forward, and some studies on it have been done. The main studying results are summarized as follows:Firstly, the feasibility of adding Al-B master alloy to the ELTA melt to prepare TiB₂/Al alloy was investigated, and the HB hardness of the prepared TiB₂/Al alloys containing different content of the TiB₂ particle was also measured. The results show that the new method is feasible. And the TiB₂ particles formated in the melt are very small and evenly present in the melt because of even distribution of the titanium atom in the ELTA. With the increase of the content of the TiB₂ particle in the alloy, the HB hardness of the TiB₂ /Al alloy is obviously increased.Secondly, the effect of the temperature on the formation of TiB₂ particle in the melt was investigated. The results indicate that agglomeration of the TiB₂ particle formed is weakened with the increase of the melt temperature from 750℃to 950℃. As a result, the TiB₂ particles becomes much finer and are distributed in the melt more uniformly, The HB hardness of the TiB₂/Al alloy is also increased. However, more Al₃Ti particles will be formed at high melt temperature, which will decrease the mechanical properties of the alloy. So the melt temperature should not be too high. The optimal temperature of preparing the TiB₂/Al alloy using the new method is about 850℃.Thirdly, the effect of excessive Ti on the microstructure of the TiB₂/Al alloy was investigated. The results show that excessive Ti may have a certain refinement effect onα-Al in the alloy. The TiB₂ particles formed are yet distributed more uniformly in the alloy due to the fineα-Al grain of the alloy. Also, the HB hardness of the alloy is increased to some extent.Fourthly, the effect of Mg element on the agglomeration of the TiB₂ particle formed in the TiB₂/Al alloy melt were studied. The results prove that adding Mg to the melt can decrease the agglomeration of the TiB₂ particles, so the TiB₂ particles become much finer and more well-distributed in the melt. The HB hardness of the Al alloy is also increased at the same time. Moreover, the Mg element can yet improve the wettability between the TiB₂ particle and Al matrix, which is beneficial to the mechanical properties of the alloy.Lastly, the Al-Si-Mg alloys with different content of the TiB₂ particle were prepared using the ELTA, Al-B master alloy, Si and Mg etc. And the in-situ formation of the TiB₂ particle in the Al-Si-Mg alloy melt and the effect of the particle on the microstructure and mechanical properties of such alloy were investigated. The results have shown that preparing applied alloy with TiB₂ particles using the new method is basically feasible. With the increase of the content of the TiB₂ particle formed, the strength of the Al-Si-Mg alloy decreases, but the plasticity obviously increases. The comprehensive mechanical property of the alloy is improved.更多还原