【作者】 戚文军； 黄正华； 郑开宏； 张新明； 刘敏； 余志明； 黄志其；

【Author】 Qi Wenjun~1,Huang Zhenghua~(1,2),Zheng Kaihong~1,Zhang Xinming~2,Liu Min~1, Yu Zhiming~2,Huang Zhiqi~3 (1.Guangzhou Research Institute of Non-ferrous Metals,Guangzhou 510650,China;2.School of Materials Science and Engineering,Central South University,Changsha 410083,China;3.Foshan Sanshui Fenglu Aluminium Co.,Ltd,Foshan 528133,China)

【机构】 广州有色金属研究院； 中南大学材料科学与工程学院； 佛山市三水凤铝铝业有限公司；

【摘要】 利用光学显微镜、扫描电子显微镜、X射线衍射仪和差示扫描量热仪分析了铸态和挤压态ZK60-xGd(x=1～3)合金的组织和相组成,测试了其硬度和室温拉伸力学性能。结果表明,随着Gd含量的增加,铸态组织逐渐细化,生成Mg-Zn-Gd新相,晶界相逐渐增多,趋于连续网状分布。硬度先显著提高,接着逐渐降低,然后又提高;抗拉强度和延伸率稍降低,屈服强度变化不大。经λ=40/T=593 K挤压后,动态再结晶晶粒逐渐增多,破碎的第二相在挤压方向上趋于带状分布,阻碍动态再结晶晶粒的长大,挤压态组织逐渐细化。硬度和综合拉伸力学性能均显著提高,抗拉强度和屈服强度逐渐提高,而延伸率逐渐降低,甚至低于铸态值(ZK60-2.98Gd合金)。挤压态合金拉伸断口形貌是典型的韧性断裂特征。更多还原

【Abstract】 Microstructures and phase compositions of as-cast and extruded ZK60-xGd(x=0～3) alloys were analyzed by optical microscope,scanning electron microscope,X-ray diffraction and differential scanning calorimetry.Meanwhile,hardness and tensile mechanical properties at ambient temperature were tested.The results show that as-cast microstructure is refined gradually with increasing the Gd content.A new phase,Mg-Zn-Gd,is formed.Phase precipitating along grain boundary increases gradually and tends to distribute by continuous network.Hardness first increases obviously,then decreases gradually and increases again.Tensile strength and elongation decrease slightly,while yield strength remains almost unchanged.After extrusion byλ=40/T=593 K,dynamic recrystallization grains increase.Broken second phase is inclined to distribute by zonal shape in the extrusion direction and hinders the growth of dynamic recrystallization grains.Extruded microstructures are refined gradually.Hardness and comprehensive tensile mechanical properties increase obviously.Tensile and yield strengths increase gradually,while elongation decreases gradually and is even lower than the as-cast value for ZK60-2.98Gd alloy. Tensile fractures of extruded alloys exhibit a typical character of ductile fracture.更多还原