| 摘要 |
The invention provides Al2O3 dispersion-strengthened Ti2AlN composites, wherein Ti2AlN matrix and Al2O3 strengthening phase both are reactively formed in situ. The volume fraction of Al2O3 is 5% to 50%; the particle size of Al2O3 ranges from 500 nm to 2 mum, with the mean size of Al2O3 particles about 0.8 mum to 1.2 mum; the shape of Ti2AlN grain is plate-like about 80 nm to 120 nm thick and 0.5 mum to 2 mum long. The composites exhibit excellent deformability at high temperature under compression and flexure stresses, and possess excellent oxidation resistance at 1100° C. to 1350° C. for long time (100 h). The composites show typical metallic conductor behavior and the electrical resistivity at room temperature is 0.3 to 0.8 muOmega.m. The invention also provides a method for preparing the same: First, nanoparticles in Ti-Al binary system were prepared in continuous way by hydrogen plasma-metal reaction (HPMR) using Ti-Al alloy rods with Al content 20% to 60% by atom, or pure Al rods and pure Ti rods. The atmosphere used in HPMR is the mixture atmosphere of nitrogen-containing gas, H2 and Ar, with total pressure of 0.8 to 1.2 atm, wherein volume ratio of H2 and Ar is 1:0.8-1.2, and volume fraction of nitrogen-containing gas is 0 to about 20%. Second, the nanoparticles were compacted by vacuum hot pressing at temperature of 800° C. to 1200° C., pressure of 40 MPa to 60 MPa, time of 4 h to 6 h, and vacuum of 2x10-2 Pa to 5x10-3 Pa.
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