MECHANISM OF FATIGUE IN CLOSE PACKED CRYSTALS.
Abstract
Face-centered cubic materials of high and low stacking fault energy were fatigued at both room temperature and liquid nitrogen temperature. Observation of the mode of crack formation, using the electron microscope together with a process of successive replication, showed that the fatigue crack begins as a series of surface cavi ties which propagate and join to form a micro crack. Application of low temperature did not change this basic behavior except to make the cavity formation process more discrete and bear a closer resemblance to the void formations ob served in high temperature creep. Such void formations have been attributed to a process of vacancy condensation. Based upon this observa tion, a low-temperature fatigue mechanism was proposed which utilizes the dislocation to sweep up point defects, created by the non-conserva tive motion of dislocation jogs, and deposit them on suitable nuclei on the external surface to form voids. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1963
- Accession Number
- AD0426562
Entities
People
- M.a. Wilkov
Organizations
- Pennsylvania State University