THRESHOLD STRESS IN CREEP OF ALUMINA-SILICON CARBIDE NANOCOMPOSITES

Tensile creep and the creep ruptures of an alumina-17 vol% silicon car bide nanocomposite at 1200 degrees C were investigated, with a particu lar interest in the behaviors at low applied stresses. At stresses of <50 MPa, the creep rates were remarkably decayed and the creep lives m ere substantially prolonged, which suggested the presence of a thresho ld stress, below which creep stopped, in the creep of the nanocomposit e. The stress was estimated to be in the range of 20-35 MPa. This thre shold stress was in agreement with that predicted from another model w here the motion of grain-boundary dislocations that were responsible f or vacancy nucleation and annihilation was considered to be pinned by hard particles.