Room-temperature strength and deformation of TiB[sub 2]-reinforced near-[gamma] titanium aluminides
- Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Materials Science and Engineering Dept.
- Martin Marietta Labs., Baltimore, MD (United States)
- BDM Federal, Inc., Arlington, VA (United States)
- Howmet Corp., Whitehall, MI (United States)
A series of TiB[sub 2]-reinforced near-[gamma] titanium aluminide (Ti-Al) matrix composites have been produced in investment-cast form and characterized with respect to microstructure and tensile deformation. The Ti-Al matrices of the composites examined are based upon the binary composition Ti-47 Al, with varying proportions of manganese, vanadium, chromium, and niobium. TiB[sub 2] has been introduced into the microstructures via XD[sup [asterisk]] processing at levels of 7 and 12 vol pct and compared to unreinforced, base variants. The influences of heat-treatment temperature and time have also been studied for each composition and reinforcement variant. The addition of dispersed TiB[sub 2] leads to a fine, stable, and homogeneous as-cast matrix microstructure. The measured TiB[sub 2] size within the composites examined ranged from 1.4 to 2.6 [mu]m. Increasing the volume fraction of TiB[sub 2] leads to increased elastic moduli, increased ambient temperature tensile strengths, and in general, increased strain-hardening response. In some instances, the overall ductility of the alloy increases with the addition of TiB[sub 2] reinforcement. The flow stresses of both the monolithic and composite variants exhibit conventional power-law plasticity. The results indicate that the strengthening and the flow behavior in these composites are derived from both indirect and direct sources. Strengthening contributions are indirectly derived from the microstructural changes within the matrix of the composite that evolve due to the presence of the reinforcement during its evolution and development, for example, due to grain refinement and reinforcement-derived interstitial solid-solution strengthening.
- OSTI ID:
- 7181004
- Journal Information:
- Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 25:10; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360602 -- Other Materials-- Structure & Phase Studies
360603* -- Materials-- Properties
ALLOYS
ALUMINIUM ALLOYS
BORIDES
BORON COMPOUNDS
COMPOSITE MATERIALS
DEFORMATION
ELASTICITY
MATERIALS
MECHANICAL PROPERTIES
MICROSTRUCTURE
TENSILE PROPERTIES
TITANIUM ALLOYS
TITANIUM BORIDES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS