Evolution of {gamma}{prime} precipitation kinetics and morphology in a Ni-13.36 at% Al alloy aged under compression
- Univ. of California, Los Angeles, CA (United States). Dept. of Materials Science and Engineering
The influence of an applied uniaxial compressive stress on the coarsening of {gamma}{prime} (Ni{sub 3}Al) precipitates at 640 C in a Ni-13.36 at.% alloy was studied experimentally. The investigation was done using cylindrical doubly-tapered monocrystalline specimens with axes of revolution parallel to [100]. At an applied load of 940 N the compressive stress varied from {approximately}30 to {approximately}130 MPa in any given specimen. Over this range of stresses the strain was primarily elastic. Dark-field transmission electron microscopy, coupled with image-analysis software, was used to characterize evolution of the {gamma}{prime} precipitate morphology, and the kinetics of coarsening in (100) were investigated for aging times up to 504 h. The authors find, quite unexpectedly, that the relationship between the kinetics of coarsening and the applied stress is not monotonic. Instead, a maximum in the coarsening rate obtains at an intermediate stress, in the neighborhood of 55 {+-} 10 MPa. Theoretical work by Johnson predicts that for certain combinations of lattice and elastic-constant mismatch, an extremum of the solubility limit exists in elastically isotropic specimens aged under uniaxial stress. The theory is not sophisticated enough to enable a quantitative comparison with experimental results, but provides some rationale for the unexpected finding.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG03-96ER45573
- OSTI ID:
- 323456
- Report Number(s):
- CONF-971201--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Computer simulation of morphological evolution and rafting of {gamma}{prime} particles in Ni-based superalloys under applied stresses
Temporal evolution of bimodal distribution of {gamma}{prime} precipitates in {und Ni}-Al-Mo alloys under the influence of coherency strains