论文部分内容阅读
生物可降解锌基合金,特别是添加合金元素的锌-镁(Zn-Mg)合金,已获得广泛研究以改善其力学性能和腐蚀性能.由于这些性能主要依赖于合金的显微组织,因此任何评价都应该从了解影响其形成的条件开始.本研究旨在探讨凝固冷却速率对Zn-1Mg-(0.5Ca,0.5Mn)(质量分数,％)合金瞬态凝固过程中显微组织演化的影响.结果表明,两种合金的显微组织均含有3种相:η-Zn枝晶基体、Zn11Mg2金属间化合物和低共熔混合物中的Zn2Mg.MnZn9和两种含Ca相(CaZn11和CaZn13)分别与Mn和Ca的添加有关.与Zn-1Mg(质量分数,％)合金相比,添加Mn和Ca元素可以细化枝晶基体和低共熔混合物.建立冷却速率、枝晶间距或共晶间距之间的关系,从而提出实验生长规律.此外,为了研究添加Ca和Mn的效果,进行硬度测试.维氏显微硬度与二次枝晶间距之间的实验相关性表明,与二元合金相比,显微组织细化和典型的Ca、Mn基金属间化合物是导致硬度增加的主要原因.“,”Biodegradable Zn-based alloys, particularly Zn-Mg alloys with the addition of alloying elements, have been intensively investigated aiming to improve both mechanical properties and corrosion behavior. Since such properties are strongly dependent on the alloy microstructure, any evaluation should commence on understanding the conditions influencing its formation. In this study, the effect of the solidification cooling rate on the microstructural evolution of Zn-1wt.％Mg-(0.5wt.％Ca, 0.5wt.％Mn) alloys during transient solidification was investigated. The results show that the microstructures of both alloys have three phases in common: η-Zn dendritic matrix, intermetallic compounds (IMCs) Zn11Mg2, and Zn2Mg in the eutectic mixture. MnZn9 and two Ca-bearing phases (CaZn11 and CaZn13) are associated with Mn and Ca additions, respectively. These additions are shown to refine the dendritic matrix and the eutectic mixture as compared to the Zn-1wt.％Mg alloy. A correlation between cooling rate, dendritic or eutectic spacings was developed, thus permitting experimental growth laws to be proposed. Additionally, hardness tests were performed to evaluate the effects of additions of Ca and Mn. Experimental correlations between Vickers microhardness and secondary dendritic spacings were proposed, showing that the microstructural refinement and characteristic Ca and Mn based IMCs induce an increase in hardness as compared to the binary alloy.