Deformation of an Alloy with a Lamellar Microstructure: Experimental.
Abstract
The deformation behavior of individual Widmanstatten colonies comprised of aligned lamellae of ductile phases has been investigated. Based on the alpha-beta Ti alloy, Ti-8Al-1Mo-1V, this study shows the existence of a large (>2X) variation in the critical resolved shear stress for yielding of individual colonies. Schmid's Law is not obeyed except for prism slip parallel to the beta lamellae. In addition, colonies with a high yield stress exhibit a high work hardening rate and fine, uniform slip, while colonies with a low yield stress deform by planar, non-uniform slip. This behavior appears to be independent of, slip system (basal, prism, or pyramidal) and of microstructure alpha-beta vs. alpha-alpha' (martensite)). The experimental behavior is correlated to several colony orientation parameters including the: stress axis, slip plane, slip direction, and orientation of the alpha-beta interface. The yield stress of a colony is found to increase as the slip direction of the dominant macroscopic slip plane tends toward being normal to the alpha-beta interface. These results indicate that the macroscopic flow behavior of colonies comprised of ductile lamellae depends on the ability of a slip system, once activated in the softer phase, to shear through the harder phase. The data also indicates that the interaction stresses at the phase interfaces are not a principle factor controlling macroscopic yielding. Finally, the alignment of a slip system in the alpha-phase with a potential slip system in the beta-phase lamellae does not appear to affect the yield stress strongly. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1980
- Accession Number
- ADA087100
Entities
People
- C. C. Wojcik
- Donald A. Koss
- K. S. Chan
Organizations
- Michigan Technological University