Thermal stress behaviors of tungsten fiber-copper composites have been studied in situ by means of X-ray diffraction technique. The composites with 50vol.% and 100μm diam. tungsten wires were fabricated by a liquid infiltration technique followed by hot rolling. The results obtained are as follows:
(1) X-ray diffraction technique was found to be an effective method to analyze the thermal stress of the composites, and both the matrix and the fiber stresses could be measured in situ which were generated due to thermal expansion mismatch of two components.
(2) Both the matrix and the fibers deformed so as to accommodate thermal expansion mismatch when the composites experienced temperature change. The resulting thermal stress in each phase satisfied an equilibrium condition, that was, the matrix stress was equal to the negative of the fiber stress since the volume fractions of both phases were equal.
(3) On thermal cycling of 282K-503K, the matrix deformed plastically and a steady state of the thermal stress-temperature hysteresis loop was achieved after only a few cycles.
