Mg、Zn在2099铝锂合金中的微合金化作用

Microalloying Roles of Mg and Zn Additions in 2099 Al-Li Alloy

研究Mg、Zn添加对一种Al-Cu-Li合金微观组织演变及力学性能的影响。结果表明,Mg、Zn的添加促进了δ′相的形核析出,并且可以降低其长大速度,因而使得合金中的δ′相更加细小弥散。在时效早期,含Mg和Zn的合金中析出大量的GP区,而不含Mg只含Zn的合金中没有看到GP区的存在,只有少量粗大的θ′相;含Mg不含Zn的合金中也有较多的GP区生成,这说明Mg促进GP区的形成,Zn单独作用对GP区形成无太大影响,只有和Mg一起作用时起到加速GP区形成的作用。随着时效的进行,含Mg和Zn的合金中GP区转变成θ′/θ′′相,而不含Mg只含Zn的合金中θ′相无明显变化,含Mg不含Zn的合金中也有大量θ′/θ′′相生成。说明Mg是促进θ′/θ′′相形成的主要元素,而Zn只是在有Mg的存在下起到促进其形成的作用。

The effect of Mg and Zn additions on the microstructure evolution and mechanical properties of an Al-Cu-Li alloy was studied by transmission electron microscopy and tensile testing. Results show that additions of Mg and Zn can accelerate the precipitation of delta' phase nucleation and inhibit its growth, so the delta' phase becomes finer and more dispersive. In the under-aging condition, a lot of GP zones are formed in the alloy containing Mg and Zn. The alloy only containing Mg also has many GP zones. But no GP zone is found in the alloy only containing Zn, while only a few coarse theta' is found. The above results reveal that Mg promotes the formation of GP zones while the single role of Zn is not significant; Zn has a better effect when it acts with Mg together. As the aging proceeding, GP zones in the alloy containing Mg and Zn transforms into theta'/theta '' phase and plenty of theta'/theta '' phases are formed in the alloy only containing Mg, but theta' phase dose not change obviously in the alloy only containing Zn. It indicates that Mg is the key element to accelerate theta'/theta '' phase formation, and Zn can promote the formation only with Mg.