α-アルミナ繊維強化アルミニウム複合材料における熱応力挙動

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Thermally induced stresses in the matrix and fibers have been studied by an X-ray diffraction technique during the thermal cycling of an α-Al_2O_3/Al composite with 50 vol % and 20 μm diam continuous FP fibers (FP is a tradename of Du Pont Company). The Al matrix contained 1.0 wt % Li to wet the fibers. After annealing the composite at 800 K for 3 hr, the in-situ thermal stress measurements were carried out at temperatures up to 580 K by the use of a vacuum resistance furnace mounted on the computer controlled Ω-diffractometer. The results obtained are summarized as follows: (1) When the composite undergoes a change in temperature, both the matrix and the fibers mechanically deform in such a way as to modify thermal expansion mismatch between two phases. The resultant thermal stress in each phase balanced with each other in the composite. (2) On cooling the composite from 580 K to room temperature (RT), the matrix showed a tensile residual stress of 50 MPa. Upon heating the composite from this stress state the matrix tensile deformation was reversed to compressive deformation. On this heating process the matrix showed a strong Bauschinger effect, that is, the matrix yielded during the unloading before being in compression. (3) On cooling the composite to liquid nitrogen temperature after cooling to RT from 580 K, and heating back to RT a compressive residual stress of -30 MPa was observed in the matrix. On the subsequent heating process the matrix plastically deformed in compression and a permanent softening due to the stress reversal had been observed in the matrix.
社団法人日本材料学会の論文
1989-06-15

α-アルミナ繊維強化アルミニウム複合材料における熱応力挙動

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