中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
Vol. 29 No. 5 May 2019 |
(State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China)
Abstract:To shorten the fabrication process of difficult-to-form TiAl sheets, twin-roll strip casting and microstructural control were investigated in Ti-43Al alloy. A crack-free sheet with dimensions of 1000 mm × 110 mm × 2 mm was obtained. The microstructure of stip casting sheets and heat treatments was systematically studied. The macrostructure consisted of columnar crystals extending inward and centrally located equiaxed crystals with severe Al segregation were observed along the thickness direction, due to the symmetrical solidification process and decreasing cooling rates. The strip casting alloy was characterized by fine duplex microstructure with a grain spacing of 20-30 μm and a lamellar spacing of 10-20 nm. Furthermore, multiple microstructures of near gamma, nearly lamellar and fully lamellar were obtained through heat treatment process with significantly improved homogeneity of the microstructure.
Key words: strip casting; TiAl alloy; sheet fabrication; microstructure characterization; heat treatment