摘要：过共晶 Al-Si 合金性能较好（ρ低，导电导热性好等）作为目前比较热门的材料之 一，在航空航天、建筑和包装等领域都有着良好的应用前景。然而，未改性的过共晶 Al-Si 合金通常非常粗糙并且性能很差。本文采用了铸锭冶金的方法制备了 Al-8Ti-2.5P-0.5C 中间合金。通过金相和 SEM、EDS 等方法得知 Al-Ti-P 中间合金对于 A390 合金具有良好 的细化效果，可以将初晶硅的平均晶粒尺寸由 110μm 降低到 18μm 左右。该细化机理是 Si 从 TiP 相的边缘开始，引起了 TiP 相的逐渐转变，形成（Al-Ti-Si）相，而 P 在基体 Al 中的溶解度小，形成 AlP 颗粒，而 AlP 颗粒可成为初晶 Si 凝固的成核底物，进而达到 细化初晶硅的目的。最后通过硬度测试得知 Al-Ti-P 变质剂细化 A390 合金的最佳时效时 间是 40 分钟左右，此时硬度达到最大 79.3HV。

关键词： Al-Ti-P 中间合金、 过共晶 Al-Si 合金、 初晶硅、 细化变质处理

毕 业 设 计 说 明 书 外 文 摘 要

Title Phase Evolution of Al-Ti-P Alloys in Hypereutectic Al-Si Alloys

Abstract：Hypereutectic Al-Si alloy has better performance (ρ low, good conductivity and so on) as one of the more popular materials, in the aerospace, construction and packaging and other fields have a good application prospects.However, unmodified hypereutectic Al-Si alloys are generally very rough and poor in performance.In this paper, A390 hypereutectic Al-Si alloy with Al-8Ti-2.5P-0.5C refined and modified was prepared by ingot metallurgy method.The results show that the Al-Ti-P master alloy has a good effect on the A390 alloy by metallographic and SEM, EDS and so on. The average grain size of the primary silicon can be reduced from 110 μm to about 18μm. The fine mechanism is that Si starts from the edge of the TiP phase and causes a gradual transition of the TiP phase to form an (Al-Ti-Si) phase, whereas the solubility of P in the matrix Al is small to form AlP particles and the AlP particles The primary crystal Si solidification of the nucleation substrate, and thus to achieve the purpose of refining the primary silicon. Finally, through the hardness test that Al-Ti-P modifier refinement A390 alloy the best aging time is about 40 minutes, then the hardness reached a maximum of 79.3HV.

Keywords  Al-Ti-P master  alloy  ， Hypereutectic Al-Si  alloy,  primary  crystalline silicon, fine metamorphic treatment

目 次

1 引言 3

1.1 过共晶 Al-Si 合金的发展现状及前景 3

1.2 过共晶 Al-Si 合金的组织及性能特点 4

1.3 提高过共晶 Al-Si 合金性能的主要途径 5

1.4 过共晶 Al-Si 合金的细化 6

1.5 课题的提出与主要研究内容 7

2 实验方法和材料的制备 9

2.1 实验材料及熔炼工艺 9

2.2 实验过程 9

3 Al-8Ti-2.5P-0.5C 母合金细化 A390 合金结果分析 11

3.1 A390 合金中初晶硅的变质 11

3.2 Al-8Ti-2.5P-0.5C 母合金对 A390 合金的细化效果 11

3.3 Al-8Ti-2.5P-0.5C 母合金的细化机理 12

3.4 材料硬度测试 14

结论