This paper investigates the effect of liquation in the partially melted zone (PMZ) on the stress–strain behaviour of the AA7075 arc fusion welds. It is identified that the presence of micro-sized Cu-rich second phases in the initial microstructure of the AA7075 is responsible for constitutional liquation in the PMZ. Although the liquation cracking can be avoided using the proper selection of filler metal, it is demonstrated that the formation of brittle Al₂Cu-type intermetallic-containing eutectic structure resulting from non-equilibrium solidification of the liquated grain boundaries can induce a severe loss of ductility in the PMZ. This calls for proper strategies to minimise the grain boundary liquid film thickness to produce a more reliable fusion weld on AA7075 alloy.

本文研究了部分熔化区 (PMZ) 液化对 AA7075 电弧熔焊缝应力应变行为的影响。结果表明，AA7075 初始微观结构中微米级富铜第二相的存在是造成 PMZ 中组成液化的原因。虽然通过选择适当的填充金属可以避免液化裂纹，但事实证明，由于液化晶界的非平衡凝固而形成脆性的 Al ₂ Cu 型金属间化合物共晶结构，会导致合金的严重损失。 PMZ 中的延展性。这就需要采取适当的策略来最小化晶界液膜厚度，从而在 AA7075 合金上产生更可靠的熔焊。