セラミック強化金属の高温衝撃破壊靭性

概要

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The impact fracture toughness K_<Id> of alumina-powder/aluminium composite and alumina-fiber/aluminium composite was measured at temperatures up to 200℃ by using a one-point bend impact tester. A fatigue precrack was introduce d in a specimen. Young's modulus, Poisson's ratio and yield stress were measured at testing temperatures, and the dynamic stress intensity factor was calculated by applying the plastic zone correction. The results are as follows: (1) as the loading rate increases, the fracture toughness of both alumina-fiber/aluminium and alumina-powder/aluminium increased. This tendency is stronger at 200℃ than at room temperature; (2) as the testing temperature increases, the K_<Ic> and K_<Id> values of both alumina-fiber/aluminium and alumina-powder/aluminium decreased. This tendency is stronger for K_<Ic> than for K_<Id>; (3) the above experimental tendencies can be qualitatively explained by taking the creep deformation of the matrix into consideration.
1991-05-25