新型变质剂及Ni对过共晶铝硅合金组织和性能的影响

摘要

The engine is the heart of the transport，the level of the domestic engine manufacturing industry is hampered by the applied materials for the piston which is used for the key components of domestic engine．The hypereutectic Al-Si alloy was used on piston in foreign country which was dependent on inport in our country．The preparing process including the ratio of content，sintering temperature，additive amount was investigated in this discussion．The modified of Al-Cu-P which was used hypereutectic Al-Si alloy was prepared by powder metallurgiced．At the same time， the effect of Ni content on the microstructure and mechanical properties was investigated．
　　The optimized prepared process for Al-Cu-P modifier was included as follow：Al and CuP content ratio：1：1；milling time：3h；milling speed：70r/min；load：320KN； packing time：3min；sintering temperature：500℃：and sintering time：1h．
　　The AlP which prelipated from Al-Cu-P modifier could be heterogeneous nucleation which leed to refined rall for primary silicon．The primary silicon can be refined from 200μm to about 30μm by Al-Cu-P modifier．Compared with the other modifier，the hardness increased by 16．5％，the room temperature strength increased by 32％．the hardness and strength further increased to 5％and 36％ relatively at room temperature after heat treatment．The modifier unchanged fracture mechanism which included typical character of intergranular and cleavage fracture．
　　Because of doped Ni element，the precipated Al3Ni was exist，with the improveing Ni content．The thermal expansion coefficient was decreased，The thermal expansion coefficient came down to 17.80×10-6/℃。
　　The alloy optimum heat treatment process：solution：500℃×3h．water quenching： 50℃，the aging procedure：200℃×8h，With the increasing of Ni content，the hardness of the cast alloy gradually increased，the largest tensile strength was obtained at 0.8％,all the alloy hardness reached to 138HV, the tensile strength was increased with the inproving of Ni content，the optimum content fall into the region of 0.8％～1.6％．The friction coefficient increases,the wear resistance is reduce with the increasing of Ni content in as-cast after adding Ni element．The wear debris is mainly composed of Al，Fe，Si，and a small amount of Fe2O3，and the wear mechanism was abrasive wear for the alloy．

目录

封面

声明

英文摘要

目录

第一章 绪 论

1.1引言

1.2合金元素对铝硅合金组织和性能的影响

1.3过共晶铝硅合金变质处理及变质机理

1.4研究意义与研究内容

第二章 实验方法

2.1实验材料

2.2实验方案与研究技术路线

2. 3过共晶铝硅合金变质剂的制备

2.4过共晶铝硅合金的制备

2.5微观结构分析

2.6物理性能分析

2.7力学性能测试

第三章 Al-Cu-P变质剂的制备及对合金组织性能的影响

3.1过共晶铝硅合金变质剂的选取与制备

3.2新型过共晶铝硅合金变质剂的优化

3.3 变质后T6处理对合金组织和性能的影响

3.4 变质机理分析

3.5 本章小结

第四章 Ni对过共晶铝硅合金组织及性能的影响

4.1含Ni过共晶铝硅合金组织分析

4.2 合金热膨胀系数

4.3显微硬度

4.4 拉伸性能分析

4.5 合金摩擦磨损性能及机理分析

4.6 本章小结

第五章 结论与展望

5.1 结论

5.2展望

参考文献

致谢

附录A：攻读硕士期间发表的论文和参与的科研项目