High-performing TiAl alloy with lamellar-network two-scale structure via semi-solid forging and its non-equilibrium solidification mechanism
TiAl alloys are lightweight, high-strength, and have good mechanical properties at elevated temperatures, rendering them appealing for high-temperature applications. However, their difficult processing, and limited ductility at ambient temperatures have hindered their widespread application. Here, w...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-05-01
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| Series: | Materials & Design |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0264127525002485 |
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| Summary: | TiAl alloys are lightweight, high-strength, and have good mechanical properties at elevated temperatures, rendering them appealing for high-temperature applications. However, their difficult processing, and limited ductility at ambient temperatures have hindered their widespread application. Here, we report fabrication of a Ti-43Al-9 V-0.3Y alloy with a novel lamellar-network two-scale structure comprising an inner α2/γ lamellar colony + outer β0/γ phases via semi-solid forging process. The formation of this lamellar-network two-scale structure is elucidated from the perspective of the solute diffusion and redistribution occurring, and occurs due to liquid segregation and a non-equilibrium transition of L → β(β0) + α at late solidification. Compared to the as-cast alloy, the semi-solid forged alloy exhibits significant increases in elongation and tensile strength at room temperature and 800°C. The high density of dislocations and mechanical twins in the β0/γ phases and special α2/γ lamellae during tensile deformation effectively release the plastic deformation potential of the TiAl alloy at room temperature. Moreover, the abundant nano-twins in the β0/γ phase and γ dynamic recrystallization behavior at 800 ℃ significantly enhance the high-temperature plasticity. This approach and microstructure offer a promising solution to the engineering challenges posed by the low room-temperature ductility and limited hot-working ability of TiAl alloys. |
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| ISSN: | 0264-1275 |