A Combined Electromagnetic Levitation Melting, Counter‐Gravity Casting, and Mold Preheating Furnace for Producing TiAl Alloy

Abstract

In this work, the authors describe the development of TiAl castings over a wide range of approaches. To overcome casting defects and cracks that appear in TiAl castings, a novel furnace is designed and constructed. The design combines induction skull melting, counter‐gravity casting, and mold heating, which facilitates both filling and microstructure formation via a controllable process. This aim is to improve shaping capabilities and microstructural control for TiAl castings. Melting and casting experiments on TiAl alloys with a nominal composition corresponding to Ti–48Al–2Cr–2Nb (at%) are carried out and discussed. X‐ray examinations indicate that the shaping of the TiAl components dose not contain macro casting defects, validating the advantages of this technique. The results are of interest to researchers devoted to technical innovations and modifications for TiAl casting at the industrial scale.

Induction Skull Melting of Ti-6Al-4V: Process Control and Efficiency Optimization

“…The ISM facility, also known as Cold Crucible Induction Melting (CCIM), is composed of a vacuum chamber in which the induction melting is performed under controlled atmosphere conditions, vacuum or inert gas [11]. The copper crucible is made of electrically insulated segments, among which magnetic fields supplied by the induction coil penetrate to the charge, heating and melting by the Joule effect (Figure 1).…”

An innovation for microstructural modification and mechanical improvement of TiAl alloy via electric current application

“…The application of an external energy field to metal liquid during solidification is a new way to change the behavior of nucleation and crystal growth and to modify the structure and enhance the mechanical properties of the solid. These fields, such as ultrasonic 1 , electromagnetic 2,3 , gravitational 4 , and electric current 5 , have shown to have great effects on the structural features and quality of cast metal. Processing technologies involving electric current are efficient, economical, and environmental methods of microstructural modification and have gained great attention in materials science, due to the resulting significant grain refinement, homogeneity and performance improvement.…”

“…TiAl alloys have attracted extensive interest among industrial companies for aeroengine applications due to the stringent requirements for higher thrust-to-weight ratios and greatly enhanced fuel efficiency 1,4,9 . TiAl are being used in the compressor part of aerospace gas turbine engines and the low pressure turbine part, because of its excellent mechanical properties.…”

“…TiAl are being used in the compressor part of aerospace gas turbine engines and the low pressure turbine part, because of its excellent mechanical properties. However, low processibility hinders the wide spread application of cast TiAl alloys 1,4,9 . Several strategies, such as the lowering of Al content to achieve fine lamellae structure, by adding rare earth elements such as Yttrium 10 and Er 11 to modify the microstructure, and the introduction of an external energy field to casting alloys 4 , were used to solve these problems.…”

“…However, low processibility hinders the wide spread application of cast TiAl alloys 1,4,9 . Several strategies, such as the lowering of Al content to achieve fine lamellae structure, by adding rare earth elements such as Yttrium 10 and Er 11 to modify the microstructure, and the introduction of an external energy field to casting alloys 4 , were used to solve these problems. We show here that refining TiAl alloys with electric current application leads to a fine-grained microstructure, and gives rise to a higher ductility and improved deformability.…”