Ti-1100 alloys were melted in a controlled atmospheric induction furnace equipped with a Ca O crucible. The microstructure, chemical composition, microhardness and metal-crucible interfacial reactions were systematica...Ti-1100 alloys were melted in a controlled atmospheric induction furnace equipped with a Ca O 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 Widmansttten 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 17 μm, respectively, which are slightly lower than those presented from microhardness tests（25 and 20 μm）. The formation of α-case was caused by interstitial oxygen atoms. The standard Gibbs energy of reaction Ca O（s）=Ca＋O for Ti-1100 alloy was also determined. The equilibrium constant and the interaction parameter between calcium and oxygen were obtained as lg K=-3.14 and eCa O =-3.54.展开更多
The variation of S content during VIM refining Ni-base superalloy using CaO crucible was studied. It was foundthat the desulphurization process could not be carried out by only using CaO crucible. The role of Al addit...The variation of S content during VIM refining Ni-base superalloy using CaO crucible was studied. It was foundthat the desulphurization process could not be carried out by only using CaO crucible. The role of Al additionto desulphurization was also studied. Combining with the results of XRD and composition analysis of the CaOcrucible, the mechanism of desulphurization was proposed. Thermodynamical calculation about the reaction betweenthe interface of CaO crucible and liquid metal has been discussed. This work indicated that under proper refiningtechnology the S content in the liquid Ni-base alloy could be reduced from 3×10-5 to 2×10-6~4×10-6.展开更多
基金Projects(51001041,51171054)supported by the National Natural Science Foundation of China
文摘Ti-1100 alloys were melted in a controlled atmospheric induction furnace equipped with a Ca O 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 Widmansttten 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 17 μm, respectively, which are slightly lower than those presented from microhardness tests（25 and 20 μm）. The formation of α-case was caused by interstitial oxygen atoms. The standard Gibbs energy of reaction Ca O（s）=Ca＋O for Ti-1100 alloy was also determined. The equilibrium constant and the interaction parameter between calcium and oxygen were obtained as lg K=-3.14 and eCa O =-3.54.
文摘The variation of S content during VIM refining Ni-base superalloy using CaO crucible was studied. It was foundthat the desulphurization process could not be carried out by only using CaO crucible. The role of Al additionto desulphurization was also studied. Combining with the results of XRD and composition analysis of the CaOcrucible, the mechanism of desulphurization was proposed. Thermodynamical calculation about the reaction betweenthe interface of CaO crucible and liquid metal has been discussed. This work indicated that under proper refiningtechnology the S content in the liquid Ni-base alloy could be reduced from 3×10-5 to 2×10-6~4×10-6.
