曲げ強さに及ぼすAl-Al_3Ni傾斜機能材料作製環境の影響評価

概要

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The strength of Al-Al_3Ni functionally graded material (FGM) has been studied through 3-point bending experiments for two different manufacturing conditions. Specimens with rectangular cross-section of 8 mm thickness×9 mm width are machined from thick-walled tube, which are manufactured in laboratory and vacuum atmosphere. They have graded compositions of Al_3Ni phase in aluminum matrix in the radial direction. The nominal volume fractions of Al_3Ni phase at the crack initiation site are V_f=41 and 15 vol.% under air, and V_f=35 and 0 vol.% under vacuum casting. Fracture of specimens occur more abruptly in the case of specimens manufactured in air than those made under vacuum condition. The fracture strengths are calculated from maximum bending load considering the graded Young's modulus and are plotted on the Weibull probability sheet. Each data set obeys a good linear relationship and the reliability of strength data is better in case of vacuum specimens. The average value of fracture stress improved with increase of volume fraction of Al_3Ni for both the manufacturing conditions. However, in the case of vacuum manufactured specimens, coefficient of variation is small. The bending strength of Al-Al_3Ni FGM is controlled by size, shape and distribution profile of Al_3Ni particles, because the cleavage fracture of Al_3Ni phase dominates the fracture process.
1998-07-25