T6处理对双辊铸轧ZK30-Y镁合金组织与性能的影响

Effect of T6 treatment on microstructure and mechanical properties of twin roll cast ZK30-Y magnesium alloy

采用双辊铸轧法制备了ZK30-Y镁合金条带,采用金相显微镜、扫描电镜、能谱仪、X射线衍射仪、显微硬度计和万能试验机研究了T6处理对ZK30-Y条带组织与性能的影响.T6处理后,组织中出现一定数量的孪晶,在组织中存在大量的第二相,主要为I-Mg3Zn6Y相和W-Mg3Zn3Y2相,它们主要以W相与I相混合的形式存在.T6处理使ZK30-Y条带的抗拉强度和屈服强度分别提高了45%和36%,延伸率得到了极大的提高,达到5.0%以上.ZK30-Y原始条带的断口存在大量的解理面,该断裂主要为脆性断裂.经过T6处理后,微小的解理面周围存在大量的韧窝,随着时效时间增加韧窝数量增加,在时效温度175℃保温5h条件下,获得了最佳的综合力学性能.

Twin Roll Cast（ TRC for short） ZK30-Y alloy strip was used in this study. The effect of T6 treatment on microstructure and mechanical properties of the ZK30-Y alloy was studied by using optical microscope,scanning electron microscopy with energy dispersive spectroscopy,X-ray diffraction instrument,microhardness tester and universal testing machine. A number of twins were obtained in TRC ZK30-Y alloy after T6 treatment. The second phases were present after T6 treatment,including the I-phase（ Mg3Zn6Y） and the W-phase（ Mg3Zn3Y2）. The W-phase always coexisted with I-phase in TRC ZK30-Y alloy. After T6 treatment,the tensile strength and yield strength were higher than those of as cast strip,which was increased by 45% and 36%,respectively. The elongation was much higher,which was beyond 5%. Many big cleavage planes were found in tensile fracture of as cast strip,which was brittle fracture. A number of dimples beside tiny cleavage planes were observed after T6 treatment. The number of dimples increased with the increasing aging time. The best mechanical properties were obtained after artificial aging at 175 ℃ for 5 hours.