Abstract
A spark plasma sintering (SPS) apparatus was used for the first time as an analytical testing tool for studying creep in ceramics at elevated temperatures. Compression creep experiments on a fine-grained (250 nm) polycrystalline magnesium aluminate spinel were successfully performed in the 1100–1200 °C temperature range, under an applied stress of 120–200 MPa. It was found that the stress exponent and activation energy depended on temperature and applied stress, respectively. The deformed samples were characterized by high resolution scanning electron microscope (HRSEM) and high resolution transmission electron microscope (HRTEM). The results indicate that the creep mechanism was related to grain boundary sliding, accommodated by dislocation slip and climb. The experimental results, extrapolated to higher temperatures and lower stresses, were in good agreement with data reported in the literature.
Highlights
The use of spark plasma sintering (SPS) has continuously expanded over the past 20 years thanks to its excellent sintering capabilities
It was reported [1] that nano-structured magnesium aluminate spinel specimens, possessing a unique combination of optical and mechanical properties, could be fabricated under a uniaxial pressure of 400 MPa at 1200 ̋ C
To the best of our knowledge, there is no data on creep behavior under conditions close to those that are applied during the high pressure SPS process
Summary
The use of spark plasma sintering (SPS) has continuously expanded over the past 20 years thanks to its excellent sintering capabilities. Sintering under high pressure allows for significant reduction of processing temperatures and fabrication of nano-structured ceramics. It was reported [1] that nano-structured magnesium aluminate spinel specimens, possessing a unique combination of optical and mechanical properties, could be fabricated under a uniaxial pressure of 400 MPa at 1200 ̋ C. The creep behavior of polycrystalline magnesium aluminate spinel and its capability to undergo superplastic deformation at relatively high temperatures (1300–1800 ̋ C). To the best of our knowledge, there is no data on creep behavior under conditions close to those that are applied during the high pressure SPS process. An SPS apparatus was used to investigate the creep behavior of magnesium aluminate spinel for the first time
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