Models of Creep in Silicon Nitride

In this section, the mechanisms of deformation that are active in two-phase materials such as silicon nitride are summarized. The grains are assumed to be completely surrounded by the secondary phase conservative creep deformation of the material -that is, no change in volume - may then occur either as a consequence of deformation of the secondary phase, or by deformation of the silicon nitride particles themselves. If the volume is not conserved - as when cavities are formed - then other mechanisms can occur. Hence, the types of deformation that can occur in the above-mentioned commercial grades of silicon nitride will be briefly discussed. 

2) For the 24 h strain, a peak was observed at about 0.8 pm, but this was swallowed up by the dominant peak, with further deformation. 

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