Micromechanisms and Micromechanics of Fracture of TiAl Intermetallics

0326071 - ÚFM 2010 RIV UA eng J - Journal Article
Dlouhý, Ivo - Chlup, Zdeněk - Hadraba, Hynek - Krahula, Karel
Micromechanisms and Micromechanics of Fracture of TiAl Intermetallics.
Metallofizika I Noveishie Tekhnologii. Roč. 31, č. 1 (2009), s. 81-96. ISSN 1024-1809
R&D Projects: GA ČR GA106/07/0762; GA ČR GD106/05/H008
Institutional research plan: CEZ:AV0Z20410507
Keywords : fracture toughness * micromechanisms of fracture * dhear ligament toughening * TiAl * intermetallics
Subject RIV: JG - Metallurgy
Impact factor: 0.089, year: 2009

The paper is focused on the analysis of the role of microstructure in fracture performance of TiAl intermetalics at room and elevated temperatures. Tensile properties, flexural strength and fracture toughness have been evaluated for Ti-40Al-2Cr-2Nb-1B and Ti-46Al-0,7Cr-0,1Si-7Nb-0,2Ni alloys. Positive Nb effect on fracture resistance was found; fracture toughness of the high Nb alloy was increased at contemporary increase of tensile and flexural strength. Fracture surfaces were evaluated using scanning electron microscopy showing the key role of mechanical twinning in deformation of both alloys. As a governing mechanism of the crack initiation a microcrack nucleation at boundaries between deformation twins and -TiAl grains was confirmed. Extensive development of shear ligament toughening was observed supplying quite good fracture toughness values in high Nb alloy. Based on findings obtained key aspects of the effect of separate microstructural components have been discussed.
Permanent Link: http://hdl.handle.net/11104/0173296