喷射成形含锰高强Al-Zn-Mg-Cu的组织和性能

利用喷射成形和热挤压的方法制备了含锰为2%(质量分数)的高强铝合金Al-8.8Zn-2.9Mg-1.6Cu合金,用X射线衍射(XRD)、光学显微镜(OM)和扫描电镜(SEM)和透射电镜(TEM)等方法研究了铝合金的微观组织,并进行了力学性能测试.研究结果表明:喷射成形制备的含锰铝合金经过热挤压和固溶处理后,基体组织为细小均匀的再结晶晶粒组织,平均尺寸约8μm.MnAl6颗粒在喷射沉积过程中沿晶界析出,经过热挤压后,尺寸大的颗粒破碎,大部分的颗粒则沿挤压方向产生一定的塑性变形.固溶处理对MnAl6颗粒尺寸的影响不明显,但棒状/片状颗粒的边角处发生球化,有利于降低诱发显微裂纹的应力或应变集中.时效后,铝合金达强度为775MPa,延伸率达4.3%,断口以细小的韧窝为主,尺寸小于500nm.

Microstructure and properties of spray-formed high-strength Al-Zn-Mg-Cu alloy containing manganese

An Al-Zn-Mg-Cu alloy containing 2% Mn (mass fraction) was prepared by spray forming method and hot extrusion. The microstructure and mechanical properties of the spray-deposited Al alloy were studied by optical microscopy, scanning electron microscopy, X-ray diffraction, and tensile tests. The results show that the Al alloy has uniformly fine recrystallized grains with an average size of 8μm after hot extrusion and solid solution treatment. MnAl6 particles were precipitated at grain boundaries during the spray forming process, most of the MnAl6 particles were plastically deformed to some extent along the direction of extrusion during the hot extrusion process, and some large MnAl6 particles were fragged. The effect of solution treatment on the size of MnAl6 particles is negligible but the spheroidization of rod-like/plate-like particles occurred at the corner of these particles. The spheroidization of MnAl6 particles is benefit to the decrease of stress or strain concentration which would induce microcracks. When aged at 120℃ for 24 h, the tensile strength of the Al alloy was increased up to 775 MPa with an elongation of 4.3%, and the fracture surface consisted mainly of dimples with a size lower than 500 nm.