摘要
在AZ91-2Ca合金中分别添加0.5%,1.0%和1.5%的Ce元素,采用重力铸造制备合金并结合组织性能分析,优化出最佳Ce含量。对最佳成分合金进行不同浇铸温度的压力铸造,对比研究Ce含量和铸造方法对AZ91-2Ca合金微观组织和力学性能的影响。研究表明:在重力铸造条件下,随Ce含量提高,合金组织明显细化,强化相Al_4Ce含量逐渐增加,进而改善了力学性能。当Ce含量为1.5%时,强度和延伸率均达到最大值。在压力铸造条件下,随浇铸温度由640℃提高到700℃,压铸AZ91-2Ca-1.5Ce合金微观组织不断细化,Al_4Ce相分布均匀,700℃压铸合金综合性能最高,抗拉强度、屈服强度和延伸率分别为191 MPa,157 MPa和1.7%。相比于重力铸造,压力铸造可进一步提高该合金的强度,从而为解决高Ca阻燃镁合金阻燃效果和力学性能之间的矛盾提供了新思路,促进了该合金在航空航天和汽车领域的应用。
The microstructure and mechanical properties of the gravity casting AZ91-2 Ca alloy are analyzed by adding 0.5%, 1.0% and 1.5% Ce respectively and the optimal Ce content is obtained. The microstructure and mechanical properties of die casting alloy are also analyzed under different pouring temperatures. The influence of the Ce content and the casting method on the microstructure and mechanical properties of AZ91-2 Ca alloy are studied. The results indicate that, for gravity casting process, the grain size of primary particles decreases, Al_4Ce phase increases, and mechanical properties are improved with the increase of the Ce content. The strength and elongation reach the maximum when the content of Ce increases to 1.5%. For die casting process, the grain size of primary particles decreases and Al_4Ce phase is uniformly distributed as the pouring temperature increases from 640 ℃ to 700 ℃. The highest ultimate tensile strength, yield strength and elongation are 191 MPa, 157 MPa and 1.7% when the temperature increases to 700 ℃. Compared with the gravity casting, the die casting can improve the strength of AZ91-2 Ca-1.5 Ce alloy. This study provides a new way to solve the contradiction between the flame retardant efficiency and mechanical properties, and promotes the application of AZ91 alloy in the fields of aerospace and automobiles.
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