Optimization of electromagnetic energy in cold crucible used for directional solidification of TiAl alloy

Abstract

Directionally solidified TiAl alloys are one of the most potential candidate for turbine blade in advanced aircraft engines. Electromagnetic (EM) cold crucible directional solidification (CCDS) is a novel technique for preparing large-size TiAl ingot without chemical contamination. In order to improve EM utilization, first the utilization of EM energy in CCDS was evaluated. Then based on the numerical calculation, the absorption power in TiAl alloy that induced by EM energy and the uniformity of EM field were studied, which contributes to the configuration design. Results indicated that the energy utilization in CCDS is improved by optimizing crucible configuration, the start-up power per square mm significantly decreases from 1250 to 500 W/mm2. Finally, a square cold crucible with the section 36 mm × 36 mm was fabricated via a configuration optimization and employed to directionally solidifying TiAl alloy. Both the surface quality and the microstructure were controlled in the processing window, suggesting that the optimization utilization of EM energy in CCDS has been achieved. The results can provide semiquantitative and experimental guidelines on the crucible design and the microstructure control of TiAl alloys from the perspective of EM energy.