Laves Phase Formation and Hardening of Martensitic Fe-9Ni-9Co-Ti Alloys.
Abstract
A new alloy series, Fe-9%Ni-9%Co with 0 to 5% Ti, has been designed to investigate the formation and hardening of Laves phases in Fe-base alloys. The general microstructural features and hardness properties were investigated after different heat treatments. In addition, the age hardening process was studied. Laves precipitates were formed in the forged, normalized, and annealed conditions. The age hardening was due to the precipitation of Laves phases from the solution-treated matrix. Maximum hardening was developed by aging the solution-treated 5%-Ti alloy at 500 C for 10 hr. No hardening response was observed in the Ti-free alloy. Both optical and scanning electron microscopy were used to follow the aging process and the morphological changes of the precipitate phases. Analysis of precipitation kinetics and morphology indicates that the nucleation of Laves phases is controlled by the martensitic substructure, particularly the martensitic lath boundaries. The level of hardening obtained is significantly greater than that reported for similar ferritic and austenitic steels.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1983
- Accession Number
- ADA129782
Entities
People
- Weily F. Chiao
Organizations
- United States Army Research Laboratory