Influence mechanism of cerium on the threshold of short fatigue crack for aluminum-lithium alloy 2090

The thresholds of short fatigue cracks for aluminum-lithium alloys 2090 and 2090+Ce are quantitatively evaluated. The essential reason resulting in stronger short crack effect has been ascertained. Influence of cerium on the threshold of short fatigue cracks for aluminum-lithium alloy 2090 was investigated. The results show that, by adding Ce into this alloy, ΔK_i and ΔK_Cl·th are increased. The influence mechanism of Ce on the threshold of short fatigue crack for alloy 2090 is explored from the bound energy, T₁ phase, the energy of anti-phase boundary, the energy of super-lattice intrinsic stacking fault and the electron bonds. By adding Ce into alloy 2090, the bound energy of Cu atom in this alloy is increased; the effect of thinning and dispersing T₁ phase is obtained; the effect of increasing the energy of anti-phase boundary and decreasing the energy of super-lattice intrinsic stacking fault for δ phase can be achieved.