Icosahedral 상을 갖는 Mg-8Zn-1.6Y 합금의 크리프 거동에 미치는 Ca 첨가 영향

• Published in: 한국주조공학회지 Vol. 40; no. 2; pp. 7 - 15
• Main Authors: 정영길, Young-gil Jung, 양원석, Wonseok Yang, 김세광, Shae K. Kim, 임현규, Hyunkyu Lim, 오건영, Gun-young Oh, 김영균, Youngkyun Kim, 김도향, Do Hyang Kim
• Format: Journal Article
• Language: Korean
• Published: 한국주조공학회 30.04.2020
• Subjects: Ca; Creep resistance; I-phase; Ignition resistance; Mg-Zn-Y alloys; 금속공학; Creep resistance; Mg-Zn-Y alloys; Ignition resistance; I-phase; Ca
• ISSN: 1598-706X; 2288-8381
• DOI: 10.7777/jkfs.2020.40.2.7

The high-temperature stability of Mg-8.0Zn-1.6Y (wt.%) alloys upon the addition of Ca has been investigated by characterizing the ignition temperature, microstructure, tensile and creep properties. The ignition temperature increases with an increase in the Ca content, indicating that an addition of Ca enhances the ignition resistance of the Mg-Zn-Y alloy. The as-cast microstructures of all tested alloys mainly consisted of the dendritic α-Mg matrix and I-phase (Mg 3 Zn 6 Y) at the grain boundaries. In the Ca-added Mg- 8.0Zn-1.6Y alloys, the Ca 2 Mg 6 Zn 3 phase forms, with this phase fraction increasing with an increase in the Ca contents. However, a high volume fraction of the Ca 2 Mg 6 Zn 3 phase rather deteriorates the mechanical properties. Therefore, a moderate amount of Ca element in Mg-8.0Zn-1.6Y alloys is effective for improving the tensile and creep properties of the Mg-Zn-Y alloy. The Mg-8.0Zn- 1.6Y-0.3Ca alloy exhibits the highest tensile strength and the lowest creep strain among the alloys investigated in the present study. The creep resistance of Mg-Zn-Y-Ca alloys depends on the selection of the secondary solidification phase; i.e., when Ca 2 Mg 6 Zn 3 forms in an alloy containing a high level of Ca, the creep resistance deteriorates because Ca 2 Mg 6 Zn 3 is less stable than the I-phase at a high temperature.