In this paper, a vacuum melting furnace which combines melting, pouring, mold preheating and heat treatment was designed and built, for the purpose of fabrication and microstructure optimization of TiAl castings. The apparatus provides the accurate control of pouring, mold preheating and subsequent heat treatment with various cooling rates, which makes the complete process from casting to final heat treatment can be carried out in one equipment and avoids the sample transfer process from casting to heat treatment device. The performance of the furnace was evaluated by casting the Ti–48Al–2Cr–2Nb and high-Nb-containing TiAl sheet and rod components. The X-ray detection images and scanning electron microscope results showed that the cavity and segregation were eliminated obviously. Significantly, an optimal nearly lamellar microstructure and fine fully lamellar microstructure were obtained, respectively. In addition, the transmission electron microscopy results show the lamellar spacing size after moving out of the heat treatment chamber is thinner than that cooling in the chamber. The results are of interest to researchers devoted to technical innovations and modifications for TiAl investment casting at the industrial scale.

本文设计并建造了一种将熔化，浇注，模具预热和热处理相结合的真空熔炼炉，以制造TiAl铸件并优化其组织。该设备可精确控制浇铸，模具预热以及随后以各种冷却速率进行的热处理，从而使从铸造到最终热处理的整个过程都可以在一台设备中进行，并且避免了样品从铸造到热处理设备的转移过程。通过铸造Ti–48Al–2Cr–2Nb和高含Nb的TiAl板材和棒状部件来评估炉子的性能。X射线检测图像和扫描电子显微镜结果表明，腔和偏析被明显消除。重要的是 分别获得了最佳的近层状组织和精细的全层状组织。另外，透射电子显微镜结果显示，从热处理室移出后的层状间隔尺寸比室内的冷却薄。研究结果对致力于工业规模TiAl熔模铸造的技术创新和改进的研究人员感兴趣。