Growth of a dislocation loop in a nonuniform field

The growth of a dislocation loop in a nonuniform field is considered at the elastic continuum level. Elementary arguments show that for many fields there exists a critical field strength below which the minimum loop size required for growth suddenly becomes very large or does not exist at all. This implies that the critical field concept applicable to strained layers can usefully be extended to other commonly occurring nonuniform fields. Several illustrative examples are discussed and studied numerically. (c) 2006 American Institute of Physics.