ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Combining in-situ tensile tests with detailed observations of fracture surfaces of atwo-phase TiAl alloy, the fracture process and fracture mechanisms of TiAl alloys are investigated.The results reveal that Cracks prefer to initiate and propagate along lamellar interfaces, which arethe weakest link in the near fully lamellar microstructure. The interlamellar strength calculated isless than the translamellar strength. The tensile stress is the driving force for crack initiation andpropagation. In specimens with a slit notch, most cracks are initiated directly from the notch rootand extended along lamellar interfaces. The main crack can be stopped or deflected into adelamination mode by a barrier grain with a lamellar interface orientation deviated from thedirection of crack propagation. In this case, new cracks are nucleated along lamellar interfaces ofgrains with favorable orientation ahead the barrier grain. The main crack and a new crack are thenlinked by the translamellar cleavage fracture of the barrier grain with increasing applied load. Inorder to extend the main crack, further increases of the applied load are needed to move the highstress region into the ligament until final fracture. The process of a new crack nucleation with abridging ligament formation decreases the crack propagation resistance rather than increases it
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.353-358.34.pdf
