Microstructural evolution and mechanical properties of network-structure Ti2AlC/TiAl composites prepared by spark plasma sintering
(1. School of Materials Science and Engineering, Taizhou University, Taizhou 318000, China;
2. School of Materials Science and Engineering, Anhui Polytechnic University, Wuhu 241000, China;
3. Key Laboratory of Air-driven Equipment Technology of Zhejiang Province, Quzhou University, Quzhou 324000, China;
4. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
2. School of Materials Science and Engineering, Anhui Polytechnic University, Wuhu 241000, China;
3. Key Laboratory of Air-driven Equipment Technology of Zhejiang Province, Quzhou University, Quzhou 324000, China;
4. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
Abstract: Ti2AlC/TiAl composites with a network structure were successfully prepared with carbon nanotubes and Ti-45Al-8Nb pre-alloyed powder using spark plasma sintering. The effects of sintering temperature (1200-1350 °C) on the microstructural evolution and mechanical properties were systematically investigated. The microstructure of Ti2AlC/TiAl composites exhibits duplex, near-lamellar, and fully lamellar structures, as the sintering temperature increases from 1200 to 1350 °C. The network structured Ti2AlC phase can refine the microstructure and the phase becomes discontinuous at high sintering temperatures. Notably, composites sintered at 1300 °C exhibit excellent mechanical properties, with the highest compressive strength (1921 MPa) and fracture strain (26%) at room temperature. Moreover, the ultimate tensile strength and fracture strain reach 537 MPa and 3.1% at 900 °C, and 485 MPa and 3.3% at 950 °C, respectively. The enhancement of the mechanical properties is attributed primarily to the load bearing, particle pull-out, and inhibition of crack propagation induced by Ti2AlC particles.
Key words: Ti2AlC/TiAl composites; microstructure; spark plasma sinter; high-temperature tensile property; strengthening mechanism