Neutron and X-ray diffraction measurements of phase stresses in SiC particulate reinforced aluminum composite

The neutron diffraction method was applied to measure the loading stress in each constituent phase of an aluminum alloy composite reinforced by silicon carbide (SiC) particles. Under uniaxial loading, the longitudinal strain measured by the neutron method increased proportionally to the applied stress, while the transverse stress decreased with the applied stress in both materials. The phase stress of the aluminum matrix and SiC particles measured by the neutron method as a function of the applied stress agreed well with the theoretical prediction by Eshelby model. The X-ray diffraction method was also applied to measure the loading and residual stresses in the same materials. The residual stress was compression for both Al and SiC phases in the composite. The diffraction elastic constants of the monolithic aluminum alloy obtained from the X-ray method are very close to those determined by the neutron method and calculated by Kroner's model. The increase in the phase stress in each phase of the composite due to uniaxial tensile loading is nearly equal to the value measured by the neutron method. The macrostress calculated from the phase stress by using the rule of mixture was equal to the applied stress.