3334 Fracture Testing of TiAl Based Alloys on the Micrometer Scale
Details
A microscale fracture testing has been applied to investigate the fracture properties of lamellar colonies in a fully lamellar Ti-46Al-5Nb-1W alloy. Micro-sized cantilever specimens with a size≈10x15x50μm^3 were prepared from one lamellar colony by focused ion beam machining. Notches with a width of 0.5μm and a depth of 5μm were also introduced into the micro-sized specimens by focused ion beam machining. Fracture tests were successfully completed using a mechanical testing machine for micro-sized specimens at room temperature. The fracture toughness values were obtained in the range 2-7MPam^<1/2>. Fracture surface observations indicate that these variations are attributable to differences in local lamellar orientations ahead of the notch. These fracture toughness values are also lower than those having been previously reported in conventional samples. This may be due the absence of significant extrinsic toughening mechanisms in these micro-sized specimens. Fracture mechanisms of these alloys are also considered on the micrometer scale.
