2024アルミニウム合金の破壊靭性および疲労き裂伝播速度に及ぼす晶出物,分散粒子の影響

抄録

Fracture toughness and fatigue crack propagation rate in 2024 alloys have been investigated through changing the morphologies of constituens and dispersoids. Fracture toughness is proportional to the square root of the spacing of constituents, mainly Cu₂FeAl₇ in 2024 alloys. Broadening the spacing from 58μm to 140μm, the fracture toughness increases by 18%. The fact that the dimple diameter becomes larger with increasing constituent spacing leads to the increase in fracture toughness. In a low ΔK region, the fatigue crack propagation rate becomes slower mainly by broadening the spacing of dispersoids, Cu₂Mn₃Al₂₀. Broadening the spacing from 0.45μm to 0.64μm, the propagation rate decreases by 50%. In a high ΔK region, on the other hand, the propagation rate becomes slower mainly by broadening the spacing of constituents.