Abstract
Mechanical properties of γ-base titanium aluminides strongly depend on microstructural parameters. Flexural strength, fracture toughness and fatigue crack growth properties were estimated for the cast and heat-treated (HT-TiAlCr) and cast, heat treated and isothermal forged (ITF-TiAlCr) chromium alloyed γ-base titanium aluminides at room temperature. HT-TiAlCr possessed superior fracture properties compared to ITF-TiAlCr. Toughening due to microcracks, and crack bridging by uncracked ligaments were observed in the test materials. Presence of lamellar grains in HT-TiAlCr increased the crack growth resistance and contributed positively to fracture properties. The coarse grain size promoted large crack deflection and fracture surface mismatch and caused high levels of crack closure in HT-TiAlCr. Combined crack-tip blunting and bridging by ductile β-phase was significant in the case of ITF-TiAlCr. Fracture mechanisms of test materials were investigated and correlated to the fracture properties.
Published Version
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