Mn变质的A380铝合金富铁相原位拉伸变形行为及断裂机理研究

Study on In-situ Tensile Deformation Behavior and Fracture Mechanism of Fe-rich Phase of Mn Modified A380 Aluminum Alloy

铝合金中不同富铁相对力学性能的影响一直是研究热点,但原位分析不同富铁相在受力过程中的变形行为则较为空白。使用0.5wt%Mn变质了A380铝合金,得到了鱼骨状α-Fe、块状α-Fe以及针状β-Fe共存的A380-0.5Mn合金。通过原位拉伸结合DIC(数字图像相关法)分析研究其受力过程中的组织变形行为,并结合断口分析总结了不同富铁相的变形机理。结果表明,鱼骨状α-Fe及周围基体均存在较小应变,位错运动为切过机制,可提高强塑性。块状α-Fe无明显应变,周围存在微应变,位错运动为绕过机制,可提高强度。平行拉伸方向的针状β-Fe及周围基体均存在较大应变,受力产生内部微裂纹,形成的新相界恶化性能;垂直拉伸方向的针状β-Fe应变较小,周围基体均存在较大应变,是由于位错塞积,产生应力集中导致开裂。

The influence of different iron-rich phases on the mechanical properties of aluminium alloys has been a hot topic of research,but in situ analysis of the deformation behavior of different iron-rich phases during stressing is relatively blank.The A380 aluminum alloy was modified by using 0.5wt%Mn.The A380-0.5Mn alloys with fishboneα-Fe,bulkα-Fe and needle-likeβ-Fe were obtained.The microstructure deformation behavior during the stress process was studied by in situ tensile analysis combined with DIC(digital image correlation method),and the deformation mechanism of different Fe-rich phases was summarized by fracture analysis.The results show that there is a small strain in both the fishboneα-Fe and the surrounding matrix,and the dislocation movement is a cut-through mechanism,which can improve the strength and plasticity.The bulkα-Fe has no obvious strain and there is micro-strain around it,and the dislocation motion is a bypassing mechanism,which can improve the strength.The needle-shapedβ-Fe in the parallel tensile direction and the surrounding matrix all have large strains,which produce internal micro-cracks and deteriorate the properties by forming new phase boundaries;the needle-shapedβ-Fe in the perpendicular tensile direction has small strains and the surrounding matrix has large strains,which are due to dislocation accumulation and stress concentration leading to cracking.