Measurement of thermal residual stresses in ZrB2-SiC composites

Neutron diffraction, Raman spectroscopy, and x-ray diffraction were employed to measure the stresses generated in the ZrB2 matrix and SiC dispersed particulate phase in ZrB2-30 vol% SiC composites produced by hot pressing at 1900 degrees C. Neutron diffraction measurements indicated that stresses begin to accumulate at similar to 1400 degrees C during cooling from the processing temperature and increased to 880 MPa compressive in the SiC phase and 450 MPa tensile in the ZrB2 phase at room temperature. Stresses measured via Raman spectroscopy revealed the stress in SiC particles on the surface of the composite was similar to 390 MPa compressive, which is similar to 40% of that measured in the bulk by neutron diffraction. Grazing incidence x-ray diffraction was performed to further characterize the stress state in SiC particles near the surface. Using this technique, an average compressive stress of 350 MPa was measured in the SiC phase, which is in good agreement with that measured by Raman spectroscopy. (C) 2011 Elsevier Ltd. All rights reserved.