组织和力学性能的影响
(大连理工大学 材料科学与工程学院，铸造工程研究中心，大连 116024)
摘 要: 研究电磁场和钙微合金化对连铸造过程中变形镁合金微观组织和力学性能的影响。利用金相显微镜(MEF-4A)、X射线衍射仪(XRD-6000)、扫描电镜(JSM-5600LV)和电子探针(EPMA-1600)对制备的连铸造锭微观组织、相组成和元素分布进行分析，并利用MTS NFW-810型试验机对连铸造锭的力学性能进行考察。结果表明：电磁场和钙微合金化复合作用能连续铸造出表面光滑、无氧化夹杂和偏析瘤的高质量铸锭，合金的微观组织得到改善，施加电磁场和钙微合金化后变形镁合金AZ61连铸锭具有晶粒细小、析出相弥散分布的均匀组织；电磁场和钙微合金化均能提高变形镁合金AZ61的抗拉强度，合金的最大抗拉强度值达到259.4MPa，较直冷连铸AZ61镁合金的提高24.2%；但钙微合金化不利于提高AZ61镁合金的伸长率。
关键字: AZ61镁合金；电磁场；微合金化；Ca
（School of Materials Science and Engineering, Foundry Research Center,
Dalian University of Technology, Dalian 116024, China）
Abstract:The continuous cast of wrought magnesium alloy AZ61 with or without electromagnetic field and microalloying of Ca was investigated. The microstructures and mechanical properties of the billets were analyzed by MEF-4A metallographic microscopy, XRD-6000 diffractometry, JSM-5600LV scanning electron microscopy, EPMA-1600 electron probe microanalyser and MTS NEW-810. The results show that the billets prepared by electromagnetic cast (EMC) and microalloying of Ca have smooth surface, and the defects, such as segregation and trapped oxide, on the billet surface can be eliminated. The microstructure is improved through applying electromagnetic cast (EMC) and microalloying of Ca，the refined grains and β-Mg17Al12 phases with small size are observed. The electromagnetic field and microalloying of Ca can improve the tensile strength, and the yield strength of AZ61 billet is 259.4MPa, increased by 24.2% compared with that of AZ61 billet by direct cold casting (DCC), but microalloying of Ca is disadvantageous to increasing the elongation of AZ61 magnesium alloy.
Key words: AZ61 magnesium alloy; electromagnetic field; microalloying; Ca
