(中南大學 粉末冶金國家重點實驗室，長沙 410083)
摘 要: 基于高強鋁合金在斷裂過程中萌生不同尺度微裂紋的機制， 用斷裂力學建立兩種尺度微裂紋影響應(yīng)力應(yīng)變場的規(guī)律， 導出高強鋁合金拉伸延性與兩種尺度微裂紋的關(guān)系，由斷裂韌性與拉伸延性的關(guān)系建立了高強鋁合金斷裂韌性與雙級微裂紋的非線性關(guān)系模型。 通過模型解析， 分析兩種尺度微裂紋體積分數(shù)對高強鋁合金斷裂韌性的影響規(guī)律。 結(jié)果表明：隨著一級微裂紋體積分數(shù)的增加， 材料的斷裂韌性開始迅速下降， 然后緩慢降低； 在較大尺度微裂紋之間萌生小尺度微裂紋， 將顯著降低合金的斷裂韌性。 將高強鋁合金的結(jié)晶相作為一級微裂紋，將彌散相和粗大析出相作為二級微裂紋， 預測高強鋁合金斷裂韌性隨兩種尺度相（微裂紋）的變化， 其規(guī)律與實驗結(jié)果較為吻合。 利用模型解析與實驗驗證結(jié)果， 提出了改善高強鋁合金斷裂韌性的組織控制方向。
關(guān)鍵字: 鋁合金； 斷裂韌性； 模型； 變形; 斷裂
high-strength aluminum alloy
containing two-scale-size microcracks
（State Key Laboratory of Powder Metallurgy,
Central South University, Changsha 410083, China）
Abstract: A fracture toughness model of high-strength aluminum alloy was established to describe the nonlinear relationship between fracture toughness and two-scale-size microcracks, based on fracture mechanics of two-scale-size microcracks initiated during aluminum alloy deformation and the derived relation between tensile ductility and two-scale-size microcracks. The model shows the effect of volume fraction of two-scale-size microcracks on fracture toughness of aluminum alloy. The fracture toughness of aluminum alloy decreases dramatically and then decreases moderately with the increase of large-scale-size microcracks. The formation of the small-scale size microcracks between the large microcracks decrease the fracture toughness sharply. The model predictions of the fracture toughness evolution of high-strength aluminum alloys with two-scale-size microcracks agree with the experimental data, with the constituents being large-scale-size microcracks and the coarse dispersoids and precipitates being small-scale size microcracks. How to improve fracture toughness of high-strength aluminum alloy was discussed based on this model.
Key words: aluminum alloy; fracture toughness; model; deformation; fracture
