Ce和Zr对新型Al-Cu-Li合金力学性能与组织的影响

The Effect of Cerium and Zirconium Microalloying Additions on the Microstructure and Mechanical Properties of a Novel Al–Cu–Li Alloy

摘要:

本文通过微观观察和拉伸测试的手段,对比研究了在一种高Cu/Li比的新型Al–5.8wt%Cu–1.3wt%Li合金中分别加入Ce, Zr或者两者共同添加对其合金的微观组织与力学性能的影响。微观观察表明：当Ce和Zr共同添加合金与单一添加Ce或者Zr的合金比较,金属间化物弥散体由粗大的多边形颗粒转变成无规则的细小粒子,相应的拉伸断口断裂模式由脆性的沿晶断裂向塑性穿晶断裂转变。进一步微观分析表明：Ce的添加促进了Al-Cu-Li合金中主要强化相T₁的析出。Ce和Zr共同添加合金与单一添加Ce合金相比,由于相对较少的Cu被束缚在尺寸较小的AlCuCe弥散体中,该合金基体中的Cu过饱和度在固溶淬火后相对更高。因此,Al-Cu-Li-Ce-Zr合金与Al-Cu-Li-Ce合金相比较其析出相种类向T₁转变,尺寸变得更小,晶粒更加细化导致了该合金在峰时效时抗拉强度,屈服强度分别相对提高了19.6%和16.1%并具有与之相当的延伸率。

Abstract:

Effects of Ce and Zr microalloying additions on the microstructure and tensile property of novel Al–5.8wt% Cu–1.3wt% Li alloys with an elevated Cu/Li ratio were investigated comparatively by microscopy methods and tensile tests. The microstructural observation showed that the intermetallic dispersoid was significantly refined from coarse polygonal shape to fine irregular particle with combinative addition of Ce and Zr compared to single addition of Ce or Zr. Due to the refinement and modification of intermetallic dispersoid， the fracture mode changed from brittle intergranular fracture to ductile transgranular fracture during tensile. In addition, microstructural analysis revealed that the addition of Ce promoted the precipitation of the T1 phase which was the predominant strengthen phase in Al-Cu-Li alloy. In comparison to Ce containing Al-Cu-Li alloy, Ce Zr-containing Al-Cu-Li alloy has raised the degree of supersaturation of Cu in matrix attributed to less Cu atom had been trapped in finer AlCuCe dispersoid after solution treatment. Thus it was found that the ultimate tensile strength (UTS) and yield strength (YS) increased by 19.6% and 16.1% respectively and with almost similar elongation (El), attributed to decreasing of the phase size, changing of precipitation type to T1 phase only and further grain refinement in Ce Zr-containing Al-Cu-Li alloy.