Microstructure of Dense Thin Sheets of gamma-TiAl Fabricated by Hot Isostatic Pressing of Tape-Cast Monotapes (Preprint)
Abstract
A powder metallurgy route based on hot isostatic pressing (HIPing) of tape-cast monotapes was used for the direct fabrication of dense thin sheets of gamma titanium aluminide. Polarized light microscopy revealed a fine-grained microstructure but a few isolated larger grains were also present. The primarily metastable alpha2 microstructure of the rapidly solidified starting powder transformed to the equilibrium near-gamma microstructure during HIPing. Chemical analysis revealed that the dense sheet had a carbon content of 0.13 wt.%, which was only 0.04 wt.% higher than that of the starting powder, but the oxygen content was significantly higher, presumably introduced during the decanning step. The hardness measured using Vickers microindentation technique was 384 +/- 9 HV. Manipulation of the as-HIPed microstructure was performed by heating for up to 1 hour in flowing argon at temperatures below and above the alpha transus. Below 1250 deg C, limited grain growth and no discernable change in the as-HIPed (near-gamma) microstructure occurred.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 2007
- Accession Number
- ADA466702
Entities
People
- A. G. Adams
- M. N. Rahaman
- Rollie E. Dutton