Superplastic Flow of Silicon Nitride-Based Nanocomposite at High Strain Rates

High-strain-rate superplasticity and low-temperature superplasticity are required for making the use of superplastic forming for engineering ceramics even more wide spread. In this study, we developed a Si 3 N 4 -based nanocomposite for the purpose of improving the superplasticity. A Si 3 N 4 -Si 2 N 2 O-TiN nanocomposite was fabricated by hot isostatically pressing the amorphous powder compact. These amorphous powder were prepared by mechanical alloying of silicon nitride and metal titanium. The compression tests were performed in the temperature range of 1573 K to 1873 K. The nanocomposite could be deformed at a strain rate of 10 -2 s -1 , which was more than 100 times faster than that available for conventional superplastic Si 3 N 4 -based materials at 1873 K. In addition, the nanocomposite was superplastically deformed in compression at low temperatures from 1573 K to 1673 K. The stress exponent and the activation energy of the nanocomposite were close to those of submicron- Si 3 N 4 -based materials.