Improvement of microstructure and mechanical properties of Al−Cu−Li−Mg−Zn alloys through water-cooling centrifugal casting technique

水冷离心铸造技术改善Al-Cu-Li-Mg-Zn合金的显微组织与力学性能

The microstructure and mechanical properties of as-cast Al−Cu−Li−Mg−Zn alloys fabricated by conventional gravity casting and centrifugal casting techniques combined with rapid solidification were investigated.Experimental results demonstrated that compared with the gravity casting technique,the water-cooling centrifugal casting technique significantly reduces porosity,refinesα(Al)grains and secondary phases,modifies the morphology of secondary phases,and mitigates both macro-and micro-segregation.These improvements arise from the synergistic effects of the vigorous backflow,centrifugal field,vibration and rapid solidification.Porosity and coarse plate-like Al13Fe4/Al7Cu2Fe phase result in the fracture before the gravity-cast alloy reaches the yield point.The centrifugal-cast alloy,however,exhibits an ultra-high yield strength of 292.0 MPa and a moderate elongation of 6.1%.This high yield strength is attributed to solid solution strengthening(SSS)of 225.3 MPa,and grain boundary strengthening(GBS)of 35.7 MPa.Li contributes the most to SSS with a scaling factor of 7.9 MPa·wt.%^(-1).The elongation of the centrifugal-cast alloy can be effectively enhanced by reducing the porosity and segregation behavior,refining the microstructure and changing the morphology of secondary phases.

研究传统重力铸造和和离心铸造结合快速凝固制备的铸态Al-Cu-Li-Mg-Zn合金的显微组织和力学性能。实验结果表明,与重力铸造相比,水冷离心铸造技术由于剧烈返流、离心力场、振动和快速凝固能显著降低孔隙率,细化α(Al)晶粒和第二相,改变第二相的形貌并降低宏观和微观偏析程度。孔隙率和粗大的板状Al13Fe4/Al7Cu2Fe相导致重力铸造合金在达到屈服点之前断裂。然而,离心铸造合金具有超高屈服强度(292.0 MPa)和中等伸长率(6.1%)。这种超高的屈服强度归因于固溶强化(SSS)和晶界强化(GBS)的共同作用,其中,SSS的贡献为225.3 MPa,GBS的贡献为35.7 MPa。比例因子为7.9 MPa·wt.%^(-1)的Li对SSS的贡献最大。通过降低孔隙率和偏析行为、细化显微组织以及改变第二相的形貌,可以有效提高离心铸造合金的伸长率。