Characterization of nanostructured Ti based intermetallics
Production, microstructural characterization and measurement of mechanical properties of nanocrystalline Ti-Al alloys are reported. Mechanical alloying and plasma-assisted sintering are used to produce these materials. The alloys investigated include TiAl+X and TiAl{sub 3}+X where X represents Cr, Mn or Fe. Mechanically alloyed powders have a microstructure consisting of an amorphous matrix and small crystalline domains. X-ray diffraction, conventional and high resolution transmission electron microscopy (TEM and HREM) are used to identify the crystallites and the amorphous matrix after different milling times. The plasma-assisted sintering technique allows production of solid specimens with low porosity. Sintered specimens have a crystalline microstructure with nanosized grains. Alloys based on TiAl-X are composed mainly of the phases {alpha}{sub 2} (DO{sub 19}) and {gamma} (L1{sub 0}), homogeneously distributed in the form of nanograins. Al{sub 3}Ti-X alloys are composed of only one cubic phase (L1{sub 2}). Mechanical properties (hardness and compression tests) measured at room temperature are reported as a function of alloy content and grain size for both types of alloys. TEM is used to characterize the deformation mechanism. Compression tests of Al{sub 3}Ti-X show no plasticity and fracture appears before any plastic behavior. However, a high fracture stress is found for the Cr and Mn-containing alloys. No dislocation activity has been identified most likely owing to the small grains produced in these alloys. The TiAl-X alloys present plasticity and have some dislocation activity owing to the relatively larger grain sizes observed.
- Research Organization:
- Ist. Politecnico Nacional, Mexico City (MX)
- OSTI ID:
- 20014222
- Resource Relation:
- Conference: 1999 TMS Fall Meeting, Julia R. Weertman Symposium: Advanced Materials for the 21st Century, Cincinnati, OH (US), 10/31/1999--11/04/1999; Other Information: PBD: 1999; Related Information: In: Advanced materials for the 21st century: The 1999 Julia R. Weertman symposium, by Chung, Y.W.; Dunand, D.C.; Liaw, P.K.; Olson, G.B. [eds.], 585 pages.
- Country of Publication:
- United States
- Language:
- English
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