摘要：
The tensile creep and creep-recovery behavior of a 0$\sp\circ$ HP SiC$\sb{\rm f}$/Si$\sb3$N$\sb4$ composite was investigated through experimentation and finite element techniques. All experiments were conducted in air at 1200$\sp\circ$C. From the experiments, a creep threshold, below which the creep rate was essentially zero, was found for stresses of 60 MPa and lower. The composite exhibited a low stress sensitivity. The stress exponent was approximately 1 for stresses between 75 and 200 MPa. Approximately 50 to 60% of the prior total strain was recovered during 50 h loading/50 h unloading cycles conducted between stress limits of 200 MPa and 2 MPa. Compared to other loading histories at the same maximum creep stress, the overall creep rate and creep strain observed for short duration symmetric loading/unloading experiments (300 s creep/300 s recovery) were significantly lower. The finite element analysis, based upon the elastic and creep properties of each constituent, considered the influence of fiber/matrix bonding and processing related residual stresses on creep and recovery behavior. The primary and steady-state behavior of the constituents were considered in the analysis. Although both 2-D and 3-D analyses predicted similar overall creep rates, a 3-D analysis was required to obtain detailed information about the stress state in the vicinity of the fiber/matrix interface. The prediction on the creep deformation was in good agreement with the experimental results. The results of the analysis showed that the tensile radial stress which develops in the vicinity of the fiber-matrix interface after processing and tensile axial stress in the matrix which develops upon loading rapidly decrease during the initial stages of creep. Both the predicted and experimental results for the composite show that 50% of the total strain which accumulated within 200 h at 200 MPa is recovered within 25 h of unloading. The residual stress in the fiber and matrix played a important r
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