(北京航空航天大學(xué) 材料科學(xué)與工程學(xué)院，北京 100191)
摘 要: 對3.5%NaCl溶液中新型含鈧Al-Mg-Cu合金的應(yīng)力腐蝕開裂宏觀性能進行測試，并對裂紋尖端的成分與微觀形貌進行分析。根據(jù)線彈性斷裂力學(xué)理論，預(yù)制疲勞裂紋試樣裂紋尖端處于平面應(yīng)變狀態(tài)，得到裂紋勻速擴展時的擴展速率、裂紋尖端應(yīng)力強度因子以及應(yīng)力腐蝕開裂強度因子的門檻值。掃描電鏡及EDS分析表明：應(yīng)力腐蝕開裂主要是沿晶擴展，預(yù)制裂紋與腐蝕介質(zhì)中的溶解氧生成Al2O3，產(chǎn)生楔入力促使裂紋擴展；裂紋尖端基體主要發(fā)生陽極溶解反應(yīng)，腐蝕產(chǎn)物以氯化鋁為主。
關(guān)鍵字: 含鈧鋁合金；應(yīng)力腐蝕開裂；強度因子
new Al-Mg-Cu alloy containing Sc
（School of Materials Science and Engineering, Beihang University, Beijing 100191, China）
Abstract:In 3.5% NaCl solution, the stress corrosion cracking properties of a new Al-Mg-Cu alloy containing scandium were examined. The composition and the micro-morphology of the crack tip were analyzed. According to the linear elastic fracture mechanics, the stress field on the crack tip of the pre-fatigue crack specimen is in a state of plane strain. The crack propagation rate as a constant speed, the stress intensity factor on the crack tip and the threshold stress intensity factor for the stress corrosion cracking are obtained. The results of the scanning electron microscopy and the EDS analyses indicate that the intergranular cracking is dominant in the stress corrosion cracking, due to the fact that the Al2O3 is formed with the oxygen dissolved in the corrosion medium around the pre-crack. Anodic dissolution reaction occurs for the matrix around the crack tip, and the corrosion products are mainly aluminum chloride.
Key words: aluminum alloy containing scandium; stress corrosion cracking; intensity factor
