ANALYSIS OF NEUTRON-DIFFRACTION PEAK BROADENING CAUSED BY INTERNAL-STRESSES IN COMPOSITE-MATERIALS

Neutron diffraction is an essential tool in the study of internal stre sses in composite materials. In most work only the peak shifts caused by the related elastic strains are considered, but other valuable info rmation exists in the form of peak shape changes. The conditions under which the pure diffraction profile of the composite (i.e. the profile when all sources of broadening not caused by the residual stresses ar e removed) represents the probability distribution of the peak shifts corresponding to the strains are examined. It is shown that in these c onditions, the pure diffraction profile has no attributes of particle size broadening (and vice versa), thereby providing a test for the val idity of results interpreted in this way. The experimental derivation of measured strain distributions in Al2O3/SiCp composites using neutro n diffraction is described. No apparent particle size broadening was d etected, demonstrating the validity of the results, which also satisfi ed other tests for consistency.