In the present study, Ti-45Al-(6, 7, 8)Nb(at%) and Ti-45Al-8Nb-0.5(Mn, Si, Y, B) alloys were prepared by arc melting and casting into Zr O2(Y2O3 stabilized) ceramic moulds to study the effect of alloying elements Nb a...In the present study, Ti-45Al-(6, 7, 8)Nb(at%) and Ti-45Al-8Nb-0.5(Mn, Si, Y, B) alloys were prepared by arc melting and casting into Zr O2(Y2O3 stabilized) ceramic moulds to study the effect of alloying elements Nb and Mn, Si, Y, B on the interfacial reaction between casting Ti Al alloys and ceramic moulds by SEM, and the elements' distribution in the interface reaction layer by line scanning. The results showed that with an increase in Nb content, the interfacial reaction weakened and the thickness of the reaction layer decreased gradually. The interface reaction thickness of the alloys with Nb content of 6, 7, 8at% were 60, 34 and 26 μm, respectively. Clearly, the addition of 8at% Nb to Ti-45 Al is the best for the thickness of the reaction layer. The addition of Nb would form a Nb-rich film in the reaction layer, which could reduce the solubility of oxygen in the interface, and suppress further diffusion of oxygen to the matrix. If the same content of Mn, Si, Y, or B alloying elements were added respectively to Ti-45Al-8Nb, the thickness of the interface reaction layer from large to small was as follows: Mn>Si>Y>B. The interface reaction thickness increased after 0.5at% Mn added, had no obvious change after 0.5at% Si addition, and decreased after adding 0.5at% Y or B. The introduced elements, which formed a protective film or/and promoted the formation of a dense aluminum oxide layer, would be of benefit to the resistance of interfacial reaction.展开更多
The production of non-weldable nickel-based superalloys,especially single-crystal superalloys,is important for additive manufacturing.Single-crystal specimens of non-weldable nickel-based superalloys were produced by ...The production of non-weldable nickel-based superalloys,especially single-crystal superalloys,is important for additive manufacturing.Single-crystal specimens of non-weldable nickel-based superalloys were produced by electron beam selective melting using an IN-738 alloy.In this study,single-crystal nickel-based superalloy specimens of diff erent sizes were prepared by a multiple preheating process and tight control of the melting parameters without the need for a grain selector or single-crystal seed for the first time.Electron backscattered diff raction measurements were performed to confi rm the presence of a single crystal.The transition boundaries between the polycrystalline and single-crystal regions at the edges and bottom of the samples were characterized to analyze the formation of single crystals.展开更多
基金supported by the National Basic Research Program of China(973 Program,No.2011CB605500)the"Fundamental Research Funds for the Central Universities"(FRF-MP-10-005B)the National Natural Science Foundation of China under Contract No.51171015
文摘In the present study, Ti-45Al-(6, 7, 8)Nb(at%) and Ti-45Al-8Nb-0.5(Mn, Si, Y, B) alloys were prepared by arc melting and casting into Zr O2(Y2O3 stabilized) ceramic moulds to study the effect of alloying elements Nb and Mn, Si, Y, B on the interfacial reaction between casting Ti Al alloys and ceramic moulds by SEM, and the elements' distribution in the interface reaction layer by line scanning. The results showed that with an increase in Nb content, the interfacial reaction weakened and the thickness of the reaction layer decreased gradually. The interface reaction thickness of the alloys with Nb content of 6, 7, 8at% were 60, 34 and 26 μm, respectively. Clearly, the addition of 8at% Nb to Ti-45 Al is the best for the thickness of the reaction layer. The addition of Nb would form a Nb-rich film in the reaction layer, which could reduce the solubility of oxygen in the interface, and suppress further diffusion of oxygen to the matrix. If the same content of Mn, Si, Y, or B alloying elements were added respectively to Ti-45Al-8Nb, the thickness of the interface reaction layer from large to small was as follows: Mn>Si>Y>B. The interface reaction thickness increased after 0.5at% Mn added, had no obvious change after 0.5at% Si addition, and decreased after adding 0.5at% Y or B. The introduced elements, which formed a protective film or/and promoted the formation of a dense aluminum oxide layer, would be of benefit to the resistance of interfacial reaction.
基金financial support from the National Key R&D Program of China(No.2017YFB1103300)。
文摘The production of non-weldable nickel-based superalloys,especially single-crystal superalloys,is important for additive manufacturing.Single-crystal specimens of non-weldable nickel-based superalloys were produced by electron beam selective melting using an IN-738 alloy.In this study,single-crystal nickel-based superalloy specimens of diff erent sizes were prepared by a multiple preheating process and tight control of the melting parameters without the need for a grain selector or single-crystal seed for the first time.Electron backscattered diff raction measurements were performed to confi rm the presence of a single crystal.The transition boundaries between the polycrystalline and single-crystal regions at the edges and bottom of the samples were characterized to analyze the formation of single crystals.
