Dislocation arrays formed during creep of heat-resistant nickel alloys

1. The second stage of creep in heat-resistant nickel alloys is due to changes in their intercrystalline structure. 2. With the same creep rate during the entire second period, which is characteristic of heat-resistant alloys containing a moderate amount of hardening phase equally distributed in the matrix, deformation is due to the gradual propagation of individual dislocations, leading to crystalline slip. 3. In alloys containing a substantial quantity of hardening phase creating a field of elastic distortion the deformation develops unevenly-the second state of creep has several sections with constant but differing rates of deformation. Each section is characterized by a different mechanism of the interaction of dislocation with growing particles of the hardening phase. 4. The low creep rate in the first section for alloy EI661 is due to pinning of dislocations around particles of γ′ phase; accelerated creep in the second section is due to the higher density of mobile dislocations; proparation of dislocations prevents particles of γ′ phase from growing together into platelets in the third stage with a lower creep rate.