화학공학소재연구정보센터
Journal of Materials Science, Vol.29, No.19, 5199-5206, 1994
Flexural Strength, Fracture-Toughness and Fatigue-Crack Growth-Behavior of Chromium Alloyed Gamma-Base TiAl
Mechanical properties of gamma-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 gamma-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 beta-phase was significant in the case of ITF-TiAlCr. Fracture mechanisms of test materials were investigated and correlated to the fracture properties.