Failure Mechanisms

· A more realistic picture of grain boundary voids is shown.

From: Ashby and Jones, "Engineering Materials I,"
Pergamon (1986)

· Once voids start to form on the grain boundaries they act as local stress concentrators. When voids are present in large enough numbers, the creep curve passes from the steady state creep range into the tertiary range, a crack forms, and the material finally fails by fast fracture.