【作者】 梅楹煜；

【导师】 陈国香； 闫洪；

【作者基本信息】 南昌大学 ， 材料加工工程， 2008， 硕士

【摘要】 镁合金因其具有质轻、高的比强度和比刚度、优良的铸造性能和机械加工性能等优点被广泛应用于汽车和航天工业中,因此,镁合金是目前研究的热点之一。同时它也表现抗拉强度低和抗高温蠕变性差等缺点,而复合材料能够改善镁合金这些性能的不足。金属间化合物Mg₂Si是镁基复合材料中的增强相。利用Mg-Si合金结晶的特点,可在凝固过程中原位生成Mg₂Si增强相,从而获得Mg₂Si/AM60镁基复合材料。然而,原位自生的Mg₂Si一般以汉字状或树枝状存在于镁合金基体中,大大影响了它的增强效果。本文在分析了Mg₂Si增强相原位形成过程的基础上,系统地研究了镁合金中Si加入量对原位Mg₂Si/AM60复合材料组织和性能的影响,并研究了金属Sb,稀土Y对复合材料中Mg₂Si相的变质效果,考察了制备的Mg₂Si/AM60镁基复合材料的抗高温蠕变性能。研究结果表明:随着AM60合金中Si含量的增加,原位自生的Mg₂Si数量增多,向AM60中添加一定量的Si后,发现组织中出现了汉字状及块状和树枝状的Mg₂Si相。通过添加金属Sb和稀土Y可以对Mg₂Si相和基体起到一定的细化作用,金属Sb和稀土Y加入后可分别生成Mg₃Sb₂相和Al₂Y相,其生成的新相能够作为Mg₂Si的异质核心,使得Mg₂Si相由汉字状变成颗粒状,并弥散地分布,获得了较理想的Mg₂Si/AM60镁基复合材料组织,改善了材料的力学性能。制备的Mg₂Si/AM60镁基复合材料比AM60基体具有较好的抗高温蠕变性能。更多还原

【Abstract】 Magnesium alloy has a great potential to be applied in automobile and aerospace industries because of their light weight, high specific strength, excellent Good cast-on outwell ability and good machine ability as compared to other structural metals. So, magnesium alloy is one of the focuses at present. But its strength and high temperature creep resistance are worse, But magnesium matrix composite is able to improve these function deficiency.Intermetallic compound Mg₂Si is an ideal reinforcing phase in metal matrix composites. Making using of the characteristics of Am60 alloy, Mg₂Si phase can be formed in the process of solidification. However, Mg₂Si often exists in the shape of coarse Chinese script in the matrix, which greatly damages the strengthening effect of Mg₂Si. On the base of the analysis of the formation process of Mg₂Si phase, the effects of Si and Al content on the microstructure of Mg₂Si/AM60 composites were systemically studied, and the modifying effect of Sb, Y on Mg₂Si phase in the composites was also studied. Finally, high temperature creep resistance of the prepared Mg₂Si/AM60 composites was investigated.The results show that with the increase of Si content in Am60 alloy, the amount of Mg₂Si in the solidified samples increases, and its shape becomes more full Chinese script. The addition of Si in the AM60 alloys the shape of coarse Chinese script is found with the addition of Si.After adding Sb and Y, the phases of AM60 and Mg₂Si phase have been refined. Mg₃Sb₂ phase andAl₂Y phase act as heterogeneous core,the shape of Mg₂Si could be transformed from the Chinese script into uniformly dispersed particles. Therefore, Mg₂Si/AM60 composites with more desirable microstructure can be obtained, as a result, the mechanical properties of the composites can be further improved and high temperature creep resistance of the composites is better than AM60 alloy.更多还原