Ti-1100高温钛合金铸造过程中与CaO坩埚的界面反应

摘要

Ti-1100 alloys were melted in a controlled atmospheric induction furnace equipped with a CaO crucible. The microstructure, chemical composition, microhardness and metal-crucible interfacial reactions were systematically investigated. The results demonstrate that the primary solidification microstructure in the as-cast alloys was the typical Widmanstätten structure. The interactions between crucible and molten alloys are attributed to slight chemical dissolution and weak physical erosion. According to the line scanning analysis, the interfacial layer (α-case) thicknesses of Ti-1100 samples in the bottom and side wall are about 18 and 17μm, respectively, which are slightly lower than those presented from microhardness tests (25 and 20μm). The formation ofα-case was caused by interstitial oxygen atoms. The standard Gibbs energy of reaction CaO(s)=Ca+O for Ti-1100 alloy was also determined. The equilibrium constant and the interaction parameter between calcium and oxygen were obtained as lgK=-3.14 andCaOe=-3.54.%研究了Ti-1100高温钛合金和CaO坩埚在可控气氛下感应熔炼时的相互作用，并对合金组织、化学成分、显观硬度以及与坩埚的界面反应进行分析。结果表明：合金的铸态组织是典型的魏氏组织。熔融金属和CaO坩埚的界面反应是由坩埚轻微的化学溶解和微弱的物理侵蚀引起的。根据线扫描分析，合金在坩埚底部和侧部界面反应区的α层厚度分别为18和17μm，这比采用硬度测试所获得的实验数据要小。α反应层的形成机制是间隙氧原子。还对Ti-1100合金CaO(s)=Ca+O反应的标准吉布斯自由能进行了测定，得到Ca和O的平衡常数和相互作用参数分别为lg K=-3.14和 CaOe =-3.54。