Creep behavior of Si3N4-whisker-reinforced Si3N4-matrix composites using an in situ dynamic beam profiling method

A four-point flexure test, capable of simultaneously measuring load-point a nd beam-center displacements and permitting in situ profiling of the beam t hroughout the test, has been developed. Compressive and tensile strains in the outer fibers, together with the neutral axis displacement, were determi ned in real time for Si3N4-whisker-reinforced Si3N4-ceramic-matrix composit es. Combining these data with the closed form solution of Chen and Chuang g ave excellent correspondence between the creep exponents determined from fl exure tests with those determined independently from tensile and compressiv e creep tests.