Effect of Rare Earth Oxide Additives on the Phase Transformation Rates of Si3N4 |
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| Authors: | Mikito Kitayama Kiyoshi Hirao Shuzo Kanzaki |
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| Affiliation: | Functional Materials Engineering, Fukuoka Institute of Technology (FIT), Fukuoka 811-0295, Japan; National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560, Japan |
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| Abstract: | Fully dense Si3N4 sintered with rare-earth (RE=La, Nd, Gd, and Yb) oxide additives were fabricated by hot pressing. They were mainly composed of the α-phase, which enabled the investigation of the α–β transformation kinetics without the effect of porosity. The phase transformation kinetics was found to be linear. The activation energies for the phase transformation were 677, 546, 487, and 424 kJ/mol for RE=La, Nd, Gd, and Yb, respectively, and showed a good correlation with the ionic radii of RE atoms, which was discussed in conjunction with the segregation behaviors of RE atoms at the interface. |
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