The effect of Mg alloying on microstructure and mechanical properties at 300 C of Al–5Cu–1Mn–0.5Ni heat-resistant aluminum alloy was investigated by microstructure observation and tensile test. Alloying with 0.5 wt%Mg addition considerably increases the yield strength at 300 C of samples at as-cast, as-solutionized and as-aged states. It also greatly enhances the strengthening effects from solution and ageing treatments, however, simultaneously, decreases the elongation greatly. During the solidification process of the alloy with Mg addition, a great amount of whisker-like Al–Cu–Mg compound phase is formed at the eutectic boundary zones in the form of ridge configuration, which is determined as AlCuMg intermetallic compound by TEM. During the solution treatment, this whisker-like AlCuMg phase is completely dissolved into Al matrix that leads to a remarkable rise in the increment of yield strength at 300 C by solution strengthening. The alloying of Mg has a significant influence on the precipitation behavior during the ageing treatment, for examples, promoting the formation of finer θ′′ particles and a great number of Cu–Mg atomic clusters. During high temperature tensile test, theses clusters evolve into fine cube-like Al₅Cu₂Mg particles with orthorhombic structure. It is the significant microstructure evolution induced by alloying of Mg that leads to the great rise in yield strength at 300 C. Addition of Mg in Al–Cu–Mn–Ni alloy dose not lead to the formation of meta-stable or stable S phase, but whisker-like AlCuMg and cube-like Al₅Cu₂Mg compounds are determined by TEM.

通过显微组织观察和拉伸试验研究了镁合金化对Al-5Cu-1Mn-0.5Ni耐热铝合金组织和300℃力学性能的影响。添加 0.5 wt% Mg 的合金可显着提高样品在 300 C 下铸态、固溶态和时效态的屈服强度。它还大大增强了固溶和时效处理的强化效果，但同时大大降低了伸长率。添加Mg的合金在凝固过程中，在共晶边界区形成了大量的晶须状Al-Cu-Mg化合物相，呈脊状排列，透射电镜确定为AlCuMg金属间化合物。在固溶处理过程中，这种晶须状的 AlCuMg 相完全溶解在 Al 基体中，通过固溶强化导致 300 C 屈服强度的增加显着增加。Mg 的合金化对时效处理过程中的析出行为有显着影响，例如，促进形成更细的θ ′′ 粒子和大量的 Cu-Mg 原子团簇。在高温拉伸试验中，这些团簇演化成具有正交结构的立方体状Al ₅ Cu ₂ Mg 颗粒。Mg 合金化导致显着的微观结构演变导致 300 C 屈服强度大幅提高。 在 Al-Cu-Mn-Ni 合金中添加 Mg 不会导致亚稳定或稳定的 S 相的形成，但须状AlCuMg 和立方体状Al ₅ Cu ₂ Mg 化合物由TEM 确定。