Determination of residual stress by neutron diffraction in 6061Al-15 vol. % � SiC w composites with different whisker orientation/distribution

The determination of residual stresses, RS, in 6061Al-15vol%SiCw composites was carried out to correlate them with whisker orientation, distribution and aspect ratio. The composites were obtained by a powder metallurgical, PM, route and consolidated by extrusion at four different temperatures, Text. This is the main parameter affecting the whisker orientation/ distribution; an increase in Text leads to an increasing whisker alignment with extrusion axis. The results of the sin2 plots account for a non-hydrostatic stress state in all composites. This is expected because of the deviatoric component of the RS tensor generated by the whisker geometry. The RS can explain the Strength Differential Effect, SDE, observed in uniaxial testing (tensile vs. compressive behaviour) of these composites.