J.M. Ehrman et al. Composites Science and Technology 67(2007)1425-1438 b) ① ② ② 50.0um 50.0m Fig 14. SEM micrographs showing placement of electron beam for the EDS analysis of N720/A specimens tested at 1200C: (a)in laboratory air and(b) ment(O nates matrix near fiber edge, (O) designates matrix interior firmed the absence of Si in the matrix In order to deter- was in direct contact with fiber prior to failure)and matrix mine whether migration of silicon species from fiber to interior (i.e. matrix located 25um away from fibers)were matrix has occurred in specimens subjected to prior testing, analyzed. Fig. 14 shows the regions of the two specimens the matrix of these specimens was examined. For each that were examined as well as locations(1)and (2)where the electron beam was focused for spectra collection Fig 15 compares the spectra of matrix near fiber edge to hose of matrix interior for specimens tested (a) in air and(b)in steam Matrix spectra of the specimen tested in T=1200℃c,Air air show a Si peak at the fiber edge but none in the matrix interior. Matrix spectra of the specimen tested in steam exhibit a considerably larger Si peak at the fiber edge and Matix Interior a slight Si peak in the matrix interior. Fig. 16 compares Matrix Near Fiber Edge the matrix spectrum of the as-processed material to the spectra of matrix near fiber edge of the tested specimens. 004 The highest Si peak is seen for the specimen tested in steam, followed by a smaller Si peak for the specimen tested in while the matrix spectrum of the as-processed material reflects the absence of Si. Results indicate that migration 2.5 a 0.10 Matrix Near Fiber Edge T= 1200C. steam 008 Matix Interior Tested in 80.06 team 002 1.01 2.02 Fig. 16. EDS matrix spectrum of the as-processed N720/A CMC Fig. 15. EDS spectra of the matrix of N720/A specimens tested at compared to matrix spectra of specimens tested at 1200C in air and in 00C:(a)in laboratory air and (b) in steam environments.The EDS analysis of the as-processed material con- firmed the absence of Si in the matrix. In order to deter￾mine whether migration of silicon species from fiber to matrix has occurred in specimens subjected to prior testing, the matrix of these specimens was examined. For each specimen, matrix located near fiber edge (i.e. matrix that was in direct contact with fiber prior to failure) and matrix interior (i.e. matrix located 25lm away from fibers) were analyzed. Fig. 14 shows the regions of the two specimens that were examined as well as locations (1) and (2) where the electron beam was focused for spectra collection. Fig. 15 compares the spectra of matrix near fiber edge to those of matrix interior for specimens tested (a) in air and (b) in steam. Matrix spectra of the specimen tested in air show a Si peak at the fiber edge but none in the matrix interior. Matrix spectra of the specimen tested in steam exhibit a considerably larger Si peak at the fiber edge and a slight Si peak in the matrix interior. Fig. 16 compares the matrix spectrum of the as-processed material to the spectra of matrix near fiber edge of the tested specimens. The highest Si peak is seen for the specimen tested in steam, followed by a smaller Si peak for the specimen tested in air, while the matrix spectrum of the as-processed material reflects the absence of Si. Results indicate that migration Fig. 14. SEM micrographs showing placement of electron beam for the EDS analysis of N720/A specimens tested at 1200 C: (a) in laboratory air and (b) in steam environment. ( ) designates matrix near fiber edge, ( ) designates matrix interior. 0.00 0.02 0.04 0.06 0.08 0.10 1.0 1.5 2.0 2.5 Energy (KeV) Normalized Counts Matix Interior Matrix Near Fiber Edge Al Si T = 1200 ˚C, Air 0.00 0.02 0.04 0.06 0.08 0.10 1.0 1.5 2.0 2.5 Energy (KeV) Normalized Counts Matix Interior Matrix Near Fiber Edge Al Si T = 1200 ˚C, Steam Fig. 15. EDS spectra of the matrix of N720/A specimens tested at 1200 C: (a) in laboratory air and (b) in steam environments. 0.00 0.02 0.04 0.06 0.08 0.10 1.01 .5 2.02 .5 Energy (KeV) Normalized Counts As-Processed Tested in Air Tested in Steam Al Si Matrix Near Fiber Edge Fig. 16. EDS matrix spectrum of the as-processed N720/A CMC compared to matrix spectra of specimens tested at 1200 C in air and in steam. J.M. Mehrman et al. / Composites Science and Technology 67 (2007) 1425–1438 1435