The machined alumina/ 20 vol.% SiC whiskers composite having a semi-circular groove was conducted to various heat-treatments. The change of the local fracture stress at the bottom of semi-circular groove has been investigated as a function of crack-healing temperature and time. By heating at 1400℃ at 10h, the machined specimen was fractured not from the cracks introduced by the hard machining but from the other region. Thus, it was concluded that the machining cracks were completely healed by the above heat treatment. Moreover, The strength at room temperature and elevated temperature (<1300℃) of the machined sample healed exhibited the same levels as that of polished sample healed. It can be demonstrated that the crack-healing was useful for an increase in the strength of machined ceramics economically.
