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摘要高硅铝合金是现代工业体系中一种重要的铸造合金，但未经变质的高硅铝合金中存在大量的长条状和树枝状初生硅相，严重切割合金基体，恶化了材料的机械性能和铸造性能，限制了高硅铝合金在工业生产中的广泛应用。因此，本文将利用机械搅拌法，并通过改变机械搅拌工艺参数和加入变质剂，来探究其对合金熔体中初生硅组织形态、大小的影响。 通过实验发现，改变机械搅拌时的搅拌速率、浇注温度以及加入变质剂都能较好改善Al-30wt%Si 合金中初生硅的形态、大小，细化初生硅颗粒。但加入过量变质剂反而会恶化初生硅组织形态。 通过实验最终得到的最佳工艺参数分别为：对于未变质 Al-30wt%Si合金，最佳工艺参数为680℃、 900r/min；对于变质后Al-30wt%Si合金，其最佳工艺参数为765℃、 900r/min；在浇注温度 765℃、搅拌速率900r/min 下，加入2gCu-P14 变质剂变质效果最佳。48046
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毕业论文关键词：高硅铝合金，机械搅拌，变质，初生硅，细化
Title Microstructure and Formation Mechanism of Hypereutectic Al-Si Alloy Prepared by Mechanical Stirring
Abstract Hypereutectic Al-Si alloy is an important casting alloys in the modern industrial system,but it has a lot of largely and dendritic primary silicon phase without modified,they will cutting the matrix seriously ,mechanical properties and casting properties, severely cutting alloy substrate, worsening the mechanical properties and casting properties of the material, limiting the hypereutectic Al-Si alloys are widely used in industrial production. Therefore, this article will use mechanical stirring, and stirring process parameters and modifiers added by changing the machinery, to explore its impact on the primary silicon alloy melt shape and size of the organization. Found through experiments, changing the stirring speed mechanical agitation, the casting temperature and the addition of modifier can better improve the Al-30wt% Si alloy shape and size of the primary silicon refinement of primary silicon particles. However, the addition of excess modifier but will worsen the primary silicon morphology. Through experiments finally obtained optimal parameters were as follows: For the unmodified Al-30wt% Si alloy, the optimum parameters for the 680 ℃, 900r / min; for the modified Al-30wt% Si alloy, the best process parameter is 765 ℃, 900r / min; in the pouring temperature 765 ℃, stirring speed 900r / min was added under 2gCu-P14 modified with the best results.
Keywords : hypereutectic Al-Si alloy, mechanical stirring, modified, primary silicon refinement
目次
1绪论.1
1.1引言1
1.2高硅铝合金的性能、组织特点1
1.3高硅铝合金的应用2
1.4影响初生硅形态的主要因素3
1.4.1冷却速率的影响3
1.4.2变质剂的影响3
1.4.3浇注温度的影响3
1.4.4搅拌速率的影响3
1.5本课题选题意义及研究内容4
1.5.1选题的科学意义及应用前景4
1.5.2本课题主要研究内容4
2实验.5
2.1实验材料及设备5
2.1.1实验材料5
2.1.2实验设备及仪器5
2.1.3实验准备6
2.2熔炼方法和原理7
2.2.1合金的熔炼7
2.2.2合金精炼的原理8
2.3实验方案9
2.3.1熔炼工艺参数的确定9
2.3.2变质工艺参数的确定9
2.4金相组织分析.11
2.4.1初生硅尺寸的测量.11
2.4.2初生硅形态的测量.12
3实验结果与分析13
3.1机械搅拌工艺对未变质铸态组织中初生硅的影响.13
3.1.1搅拌速率对未变质铸态合金组织中初生硅的影响.13