Key Takeaways & Executive Findings
- •• Multi-scale Ti2AlC/TiAl composites were successfully fabricated via vacuum arc melting and heat treatment, achieving micro-, submicro-, and nano-scale reinforcements. • Optimal high-temperature tensile properties were achieved with 2 at.% graphite addition, yielding a tensile strength of 561 MPa and elongation of 3.6%. • Micro-Ti2AlC inhibits grain boundary softening and hinders dislocation motion, while submicro-Ti2AlC prevents twin propagation and obstructs dislocation motion. • Nano-Ti2AlC hinders dislocation movement and fine-tunes the lamellar microstructure, contributing to enhanced mechanical performance.
Abstract
The multi-scale Ti2AlC/TiAl composites were fabricated. Micro-Ti2AlC particles are obtained in-situ at the grain boundaries of the full lamellar TiAl matrix by vacuum arc melting. The targeted precipitation of submicro-Ti2AlC at the lamellae TiAl/Ti3Al phase boundary and directional precipitation of nano-Ti2AlC within TiAl crystals are achieved by heat treatment. And the best high-temperature tensile properties are obtained when the graphite powder is added at 2 at.%, resulting in a tensile strength of 561 MPa and an elongation of 3.6%. These findings underscore the multifaceted role played by the multi-scale Ti2AlC: micro-Ti2AlC effectively inhibits grain boundary softening and hinders dislocation motion, while submicro-Ti2AlC prevents twin propagation and obstructs dislocation motion. Nano-Ti2AlC, on the other hand, not only hinders dislocation movement but also fine-tunes the lamellar microstructure.
1. Introduction
With the rapid advancements in the aerospace field, the development of a high-temperature, lightweight structural material with exceptional mechanical properties has become an undeniably formidable challenge, aimed at fulfilling the stringent requirements of high-performance, energy-efficient engines [1−4]. TiAl alloys stand as promising contenders for high-strength applications under extreme temperatures, particularly in aircraft engines, attributed to their enviable properties like low density, high melting point, superior creep resistance, and unparalleled oxidation/corrosion resilience [5−9]. Since 2011, the GEnx™ engines have been employing the Ti−48Al−2Cr−2Nb (4822) alloy, a second-generation intermetallic compound, for the casting of their low-pressure turbine blades, thereby enhancing performance and durability [10].
Certainly, while TiAl alloys have gained early industrial production and application in aerospace engines, their potential for large-scale industrial utilization remains constrained owing to two significant limitations: their limited plasticity at room temperature and inadequate strength under high-temperature conditions [11−13]. To realize more efficient engines in the future, it is indispensable to optimize mechanical properties of these alloys and expand their operational horizons. Over the past decades, significant advancements have been made in enhancing the mechanical properties and ductility of metallic materials, achieved through the application of alloying, thermal-mechanical processing, heat treatment, and composite technology [14−18]. To enhance the mechanical performance and operating temperature range of TiAl alloys, WANG et al [19] successfully synthesized dual-scale Ti2AlC particle-reinforced TiAl composites through the utilization of pre-alloyed Ti−48Al−2Nb−2Cr powders and multi-walled carbon nanotubes, employing the advanced spark plasma sintering (SPS) method. The TiAl composites exhibited remarkable mechanical properties, both at ambient and elevated temperatures. Notably, the composites achieved an ultra-high tensile strength of 599.6 MPa at 800 °C, surpassing the strength of TiAl matrix by 28.3%, while maintaining an unchanged strain at break of 4.2%. GUO et al [20] conducted heat treatment processes to significantly enhance the high-temperature mechani...
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Zhe DENG, Pei LIU, Zhi-yong ZHANG, Ai-qin WANG, Jing-pei XIE, Zhen-bo WANG (2025). Fabrication, microstructure and high-temperature strengthening mechanism of multi-scale Ti2AlC/TiAl composite. SinoTechIntel Verified Research. https://doi.org/10.1016/S1003-6326(25)67021-X
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Frequently Asked Questions
What is the main focus of this research?
The research focuses on the fabrication, microstructure, and high-temperature strengthening mechanism of multi-scale Ti2AlC/TiAl composites, aiming to enhance the mechanical properties of TiAl alloys for aerospace applications.
How were the multi-scale Ti2AlC/TiAl composites fabricated?
The composites were fabricated using vacuum arc melting to obtain micro-Ti2AlC particles in-situ at grain boundaries, followed by heat treatment to achieve submicro- and nano-Ti2AlC precipitations at specific locations within the lamellar structure.
What were the optimal high-temperature tensile properties achieved?
The best high-temperature tensile properties were achieved with 2 at.% graphite powder addition, resulting in a tensile strength of 561 MPa and an elongation of 3.6%.
What are the roles of different scale Ti2AlC reinforcements?
Micro-Ti2AlC inhibits grain boundary softening and hinders dislocation motion; submicro-Ti2AlC prevents twin propagation and obstructs dislocation motion; nano-Ti2AlC hinders dislocation movement and fine-tunes the lamellar microstructure.
Why are TiAl alloys important for aerospace applications?
TiAl alloys are important due to their low density, high melting point, superior creep resistance, and excellent oxidation/corrosion resilience, making them suitable for high-temperature components like turbine blades.
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