Cold pressing and conventional sintering was used to prepare an Al-Cu-Mg alloy and the effects of isothermal sintering time at 620℃ on evolution of the microstructure were studied. The results showed that at an isothermal sintering time of 30 min, the eutectic liquid of Al-Mg, Al-Cu-Mg and Al-Cu filled the particle gaps, resulting in a reduction of pores and rapid densification of the alloy; at isothermal sintering times of 30−120 min, the grains began to grow continuously which increased the density of the alloy a little; at 180 min, a large number of micropores appeared in the alloy which caused the density to decrease. Examination of the alloy micro-area elements showed that Cu diffused from the grain core to the grain boundary during sintering, which promoted the hard and brittle θ phase at the grain boundary. This increased the grain boundary strength and hence the tensile strength and hardness of the alloy. At an isothermal sintering time of 180 min, the strength of the alloy decreased. Optimum mechanical properties of the alloy were obtained at an isothermal sintering time of 120 min, the tensile strength and elongation were 237.9 MPa and 12.67% respectively, and the hardness was 87.7 HBW. A spinel phase, observed at the grain boundary of the aluminum alloy, provided evidence for the role of Mg in destroying the oxide film to promote sintering of the liquid phase.

采用冷压和常规烧结法制备了Al-Cu-Mg合金，研究了620℃等温烧结时间对组织演变的影响。结果表明，在等温烧结30 min时，Al-Mg，Al-Cu-Mg和Al-Cu的共晶液体填充了颗粒间隙，导致孔的减少和合金的快速致密化。在30-120分钟的等温烧结时间下，晶粒开始连续生长，这使合金的密度有所增加。在180分钟时，合金中出现大量微孔，导致密度降低。对合金微区元素的检查表明，在烧结过程中，Cu从晶核扩散到晶界，从而促进了晶界处的硬而脆的θ相。这增加了晶界强度，从而提高了合金的拉伸强度和硬度。在等温烧结时间为180分钟时，合金强度降低。在120分钟的等温烧结时间下，该合金具有最佳的机械性能，拉伸强度和伸长率分别为237.9 MPa和12.67％，硬度为87.7 HBW。在铝合金晶界处观察到的尖晶石相为镁在破坏氧化膜，促进液相烧结中的作用提供了证据。抗拉强度和伸长率分别为237.9 MPa和12.67％，硬度为87.7 HBW。在铝合金晶界处观察到的尖晶石相为镁在破坏氧化膜，促进液相烧结中的作用提供了证据。抗拉强度和伸长率分别为237.9 MPa和12.67％，硬度为87.7 HBW。在铝合金晶界处观察到的尖晶石相为镁在破坏氧化膜，促进液相烧结中的作用提供了证据。