2024铝合金的铸态组织均匀性及其对力学性能的影响

Microstructure and mechanical properties of as-cast 2024 aluminum alloy ingot

利用直读光谱仪、光学显微镜(OM)、扫描电镜(SEM)、能谱分析仪(EDS)、硬度计及室温拉伸万能试验机等设备,系统研究了航空用2024铝合金铸锭不同位置的成分、微观组织及其力学性能.研究结果表明:2024铝合金铸锭组织主要为αAl基体及在αAl基体中大量弥散的强化相.此外,αAl晶界及枝晶间还存在着在凝固过程中形成的αAl+Al 2CuMg(S)共晶组织、αAl+Al 2Cu(θ)共晶组织和少量的Al 6(Mn,Fe)脆性相,并且从铸锭心部至边部,Al 2Cu和Al 6(Mn,Fe)相的尺寸减小,数量减少.成分与组织上的差异使铸锭边部的抗拉强度和延伸率明显高于心部.

The composition,microstructure and mechanical properties of as-cast 2024 aluminum alloy ingot at different positions have been studied by means of direct reading spectrometer,optical microscope(OM),scanning electron microscope(SEM),energy spectrum analysis(EDS),hardness test and room temperature tensile test.The results show that the microstructure of 2024 alloy consists ofα-Al matrix and a large amount of tiny strengthening phases in theα-Al matrix.In addition,the eutectic structureα-Al+Al 2CuMg(S),eutectic structureα-Al+Al 2Cu(θ)and a small amount of Al 6(Mn,Fe)brittle phase formed in the process of solidification exist in the grain boundary and dendrite ofα-Al.Moreover,the size and number of Al 2Cu and Al 6(Mn,Fe)decrease from the center to the edge of the ingot.The difference in composition and microstructure results in higher tensile strength and elongation at the edge of the ingot than that of the center.