Fracture toughness testing of TiAl base intermetallic alloys

Fracture toughness of a light weight #gamma#-TiAl base intermetallic alloy with a duplex microstructure has been investigated at room temperature. Single edge notch bend specimens of various sizes and compact tension specimens were tested both with EDM slit notches and fatigue precracks. The loading rate was varied to study the rate effect on fracture resistance. The present investigator, showed that the inhomogeneity in microstructure needs to be considered in fracture toughness characterisation of TiAl base intermetallics. The crack length measurement needs to be improved. The test loading rate and notch root radius #rho##<=#0.05 mm had no observable effect on the deformation behaviour and fracture resistance of the material. The fracture toughness data showed specimen size and geometry dependence. The crack growth data from CT specimens were correlated with fracture parameters K, J and CTOD. The applicability of the existing methods for testing metals in fracture toughness characterisation of TiAl intermetallics is discussed. (orig.)Special print from: Engineering Fracture Mechanics, 56(1997)2, p. 155-165. Published by Elsevier (Netherlands)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman