Abstract
We investigated the high-P,T annealing and mechanical properties of nanocomposite materials with a highly nitrided bulk composition close to Ti3N4. Amorphous solids were precipitated from solution by ammonolysis of metal dialkylamide precursors followed by heating at 400-700 oC in flowing NH3 to produce reddish-brown amorphous/nanocrystalline materials. The precursors were then densified at 2 GPa and 200-700 oC to form monolithic ceramics. There was no evidence for N2 loss during the high-P,T treatment. Micro- and nanoindentation experiments indicate hardness values between 4-20 GPa for loads ranging between 0.005-3 N. Young's modulus values were measured to lie in the range 200-650 GPa. Palmqvist cracks determined from microindentation experiments indicate fracture toughness values between 2-4 MPa·m1/2 similar to Si3N4, SiC and Al2O3. Significant variations in the hardness may be associated with the distribution of amorphous/crystalline regions and the very fine grained nature (~3 nm grain sizes) of the crystalline component in these materials.
Original language | English (US) |
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Pages (from-to) | 1747-1762 |
Number of pages | 16 |
Journal | Materials |
Volume | 4 |
Issue number | 10 |
DOIs | |
State | Published - 2011 |
Keywords
- High pressure
- Metal nitrides
- Microhardness
- Nanocomposite materials
- Nanoindentation
- Synthesis
- TiN
ASJC Scopus subject areas
- Materials Science(all)