Abstract
Using pure Ti, Al and TiN powders as starting materials, TiAl base composites were produced by MA-HIP method. Microstructures and mechanical properties at elevated temperatures were investigated for HIPed compacts in addition to the MA process. Results are as follows. Though the mixed state was mostly maintained even after MA treatment, the formation of amorphous phase was confirmed in part. With the increase of volume percent of TiN particles, microstructures of HIPed compacts became finer. Ti2AIN phase was observed as well as TiAl and Ti3Al phases for compacts for which TiN was added initially. This shows the occurrence of the reaction between TiAl and TiN during sintering. The flow stress was increased with increase of TiN volume percent and the effect of dispersion strengthening was not on the decline at higher temperatures. The strain rate sensitivity exponents (m values) were found to be 0.45 at 1373K for matrix and 10vol%TiN alloys, suggesting the development of superplasticity.
