Mg-Zn-Y-Zr合金热裂敏感性的研究  

Hot Tearing Susceptibility of Mg-Zn-Y-Zr Alloys

作　　者：黄张洪[1] 张燕[2] 陈荣石[1] 韩恩厚[1] 

机构地区：[1]中国科学院金属研究所金属腐蚀与防护国家重点实验室,辽宁沈阳110016 [2]中国兵器工业第五九研究所,重庆400039

出　　处：《铸造》2009年第8期788-792,共5页Foundry

基　　金：国家自然科学基金(50574086);国家973计划(2007CB613704)资助

摘　　要：由于镁合金凝固温度区间很长,所以容易产生热裂。作为新型的高强度变形镁合金,Mg-Zn-Y(ZW系)合金在半连续铸造过程中极易发生热裂。采用"CRC"(Constrained Rod Casting)铸造热裂试验及冷却曲线热分析方法研究了ZW系中ZW22、ZW42、ZW44、ZW26、ZW62合金的凝固路径,凝固最后阶段剩余液相分数以及锆细化等因素和其热裂倾向的关系。热裂纹位置因子、宽度因子等热裂敏感性因子的表征结果表明,合金的热裂倾向从大到小顺序为:无Zr的ZW62>ZW62>ZW22,ZW42和ZW44>ZW26合金。无Zr的ZW62合金比其他合金具有更大热裂倾向与几方面因素有关:具有最长的凝固温度区间;从枝晶干涉点到凝固终了温度间形成W相,阻碍枝晶间剩余液体的流动性,不利于枝晶间补缩;最后凝固阶段剩余液相最少,且该阶段固相分数随温度降低增长缓慢;粗大组织和发达的枝晶。Magnesium alloys are prone to hot tearing basically due to their long solidification range. Ternary Mg-Zn-Y （ZW series） alloys are the base of some new high strength wrought magnesium alloys and tend to hot tearing during DC casting. Some of ZW alloys including ZW22, ZW42, ZW44, ZW26 and ZW62 alloys are selected, aiming at understanding the relationship among hot tearing susceptibility and solidification pathways, residual liquid at the last stage of solidification and Zr refinement etc. by constrained rod casting （CRC） in a steel mold and cooling curve thermal analysis. Hot tearing susceptibility is found in the investigated alloys as follows： ZW62 without Zr addition〉ZW62〉ZW22, and both ZW42 and ZW44〉ZW26. The highest hot tearing susceptibility of ZW62 alloy without Zr addition releates to the following reasons： the longest freezing range; after dendrite coherency, the formation of W-phase worsen the liquid flow and interdendritic feeding; less residual liquid and the solid fraction increasing slowly in the last stage of solidification; bulky and well-branched dendritic grains.

关 键 词：MG-ZN-Y-ZR合金 糊状区 冷却曲线 热分析 热裂 

分 类 号：TG131[一般工业技术—材料科学与工程]