Microstructure and interface reaction of investment casting TiAl alloys
(1.National Key Laboratory for Precision Hot Processing of Metals, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
2.黑龙江省哈尔滨市哈尔滨工业大学材料科学与工程学院精密金属热加工国家重点实验室)
2.黑龙江省哈尔滨市哈尔滨工业大学材料科学与工程学院精密金属热加工国家重点实验室)
Abstract: In order to research the microstructure of TiAl alloy and TiAl-mould reaction between TiAl and ceramic mould shells prepared with the low cost binder in investment casting, the ceramic mould shells were prepared with low cost binder and refractory materials. Using two kinds of casting methods (gravity casting and centrifugal casting), the titanium aluminum alloys with rare earth element (Ti-47.5Al-2Cr-2Nb-0.3Y and Ti-45Al-5Nb-0.3Y) were cast into the mould shells. The microstructures of investment casting titanium aluminum alloys were observed by optical microscope (OM). The distributions of elements of topping investment on the surfaces of titanium aluminum alloys castings were analyzed by the means of electron probe micro-analysis (EPMA), and the mechanical properties were studied. The results show that the microstructures of two kinds of titanium aluminum alloys are both lamella shape, and lamella is thin. The thickness of reaction and diffusing layer of Ti-47.5Al-2Cr-2Nb-0.3Y alloy is about 80 μm, and that of Ti-45Al-5Nb-0.3Y is less than 30 μm.
Key words: titanium aluminum; investment casting; microstructure; reaction