Microstructure and Mechanical Properties of Spark Plasma Sintered Nanocrystalline TiAl-xB Composites (0.0 <x<1.5 at.%) Containing Carbon Nanotubes

• Published in: Journal of materials engineering and performance 2021-06, Vol.30 (6), p.4380-4392
• Main Authors: Mohammadnejad, Ali, Bahrami, Abbas, Tafaghodi Khajavi, Leili
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Engineering Design; Materials Science; Quality Control; Reliability; Safety and Risk; Tribology
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-021-05773-6

This paper investigates the effects of minor additions of carbon nanotubes (CNTs) and boron on the structure and mechanical properties of nanocrystalline TiAl intermetallic compound. Nanocrystalline TiAl- x B(0.0 < x < 1.5 at.%) composites containing 1 wt.% CNT were synthesized by mechanical alloying and spark plasma sintering. Microstructure and mechanical properties of samples were evaluated using a scanning electron microscopy, energy-dispersive x-ray spectroscopy, elemental mapping, differential scanning calorimetry, Vickers hardness measurement, and shear–punch test. The findings of the current study show that milling up to 40 h results in the formation of Ti(Al) solid solution. Further milling up to 60 h is associated with a complete amorphization of the structure. Results also show that spark plasma sintering leads to the transformation of Ti(Al) solid solution into a mixture of Ti 3 Al, Ti 2 Al, and TiAl intermetallic compounds. Minor additions of boron and CNTs cause a significant grain refinement. The addition of the latter significantly improves the elongation as well. The implications of boron/CNT additions for the microstructure of TiAl and how it correlates with the mechanical properties are thoroughly discussed in this paper.