Fundamental Studies of Beta Phase Decomposition Modes in Titanium Alloys
Abstract
A TEM investigation of the interphase boundary structure of (hcp) grain boundary alpha allotriomorphs in a titanium-7.15 W/O chromium alloy has shown that whether these crystals are Burgers or non-Burgers-related with respect to their bounding (bcc) beta matrix grains their interfacial structures are partially coherent. No misfit dislocations are observed at either type of interface. Instead, two types of ledge are present. One type is widely and irregularly spaced and heavily kinked; this appears to be growth ledges. The other type are quite straight and both closely and uniformly spaced; this is likely to be structural ledges. Habit plane measurements on the broad faces of alpha plates support the presence of structural ledges. These ledges have a Burgers vector of a/6 (111) parallel to the terrace plane, indicating that they can perform as significant compensators of misfit dislocations. Studies on the interphase boundary structure of the BCC/HCP massive transformation in a silver-26 A/O aluminum alloy have reached the point where a technique for preparing thin foils in a manner which permits a significant number of interfaces to be imaged has finally been achieved. Studies of this structure have now been inititiated.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 31, 1989
- Accession Number
- ADA205296
Entities
People
- H. I. Aaronson
- T. Furuhara
- Y. Mou
Organizations
- Carnegie Mellon University