作　　者： (王志）; (周野）; (周乐）; (李一洲）; (毛萍莉）; (刘正）; (王峰）;

机构地区： 沈阳工业大学材料科学与工程学院,沈阳110870

出　　处： 《材料研究学报》 2017年第8期561-568,共8页

摘　　要： 采用具有凝固收缩力和凝固温度采集系统的约束杆(CRC)热裂测试装置研究了Ca和Y(2%,3%,质量分数)两种元素对Mg-1.5Zn合金热裂行为的影响,并通过石蜡渗透法测定合金裂纹体积。实验结果表明Mg-1.5Zn合金中添加Ca和Y元素后,由于脆弱区凝固温度范围缩小(△T)使合金的热裂敏感性(HTS)显著降低。另外,随着Ca和Y含量的增加合金的热裂敏感性进一步降低。通过热裂区域的微观组织观察发现由于MgZn-3Ca和Mg-1.5Zn-3Y合金的低熔点共晶相增多使热裂纹可以在凝固末期被共晶液相补缩。热裂纹的微观断口表明热裂是由于凝固末期枝晶分离和液膜撕裂引起的,并且沿着晶界萌生和扩展。 The effect of Ca or Y（2 % and 3 %, mass fraction, respectively） on hot tearing behavior of Mg-1.5% Zn alloy was investigated using a constrained rod casting（CRC） apparatus equipped with a load cell and data acquisition system. Tear volumes were quantified by wax penetration method. The experimental results show that the addition of Ca or Y could significantly decrease the hot tearing susceptibility（HTS） of the Mg-1.5Zn alloys due to that they could reduce the solidification temperature range（ΔT）for vulnerable regions. The reduction in ΔT may correspondingly imply the decrease of the HTS. In addition, the HTS further reduces with the higher amount of Ca or Y. It is observed that some of the formed cracks are possible to be healed by the subsequent refilling of the remained liquids during the final solidification stage, while the propagation of hot cracks along the dendritic and grain boundaries may be ascribed to the interdendritic separation or liquid film rupture.

关 键 词： 金属材料 热裂敏感性 裂纹体积 液膜 共晶液相