(1. 北京科技大學(xué) 新金屬材料國家重點實驗室，北京100083；
2. 寶山鋼鐵股份有限公司 中央研究院 寶武鋁業(yè)技術(shù)中心，上海 201900；
3. 中國寶武三門峽鋁基新材料研發(fā)中心，三門峽 472000)
摘 要: 通過SEM、TEM觀察及性能測試等手段研究了Al-Mg-Si-Cu-(2.0%Zn)合金析出和抗晶間腐蝕行為。結(jié)果表明：添加Zn可有效促進預(yù)時效態(tài)合金185 ℃時效初期硬化速率和峰值強度(峰值硬度、屈服強度和抗拉強度分別可達1200 MPa、313.9 MPa和358.8 MPa)，但是伸長率卻降低不明顯，SEM斷口形貌呈典型的塑性斷裂特征；添加2.0%Zn的峰時效態(tài)合金還具有優(yōu)異的抗晶間腐蝕性能，最大晶間腐蝕深度可由不含Zn合金的90 μm降低至40 μm。TEM組織表征顯示，溶質(zhì)元素Zn的添加可以顯著促進合金晶內(nèi)和晶界沉淀相的析出，晶內(nèi)仍以Mg-Si沉淀相為主，而晶界附近分布有Mg-Zn沉淀相，偏離晶界較遠處卻分布有由多種元素構(gòu)成的AlMgSiCuZn沉淀相；基于組織和性能演化規(guī)律，提出了含2.0%Zn合金晶內(nèi)和晶界沉淀析出過程模型圖，及其相關(guān)抗晶間腐蝕影響作用機制。
關(guān)鍵字: Al-Mg-Si-Cu-Zn合金；時效響應(yīng)；峰時效；晶間腐蝕；模型；機制
（1. State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China;
2. Baowu Aluminum Technical Center, Baosteel Central Research Institute, Baoshan Iron & Steel Co., Ltd., Shanghai 201900, China;
3. Sanmenxia Aluminum-based New Material Research & Development Center, China Baowu Steel Group, Sanmenxia 472000, China）
Abstract:In this work, the precipitation and corrosion behaviors of Al-Mg-Si-Cu-(2.0%Zn) alloys were studied through SEM, TEM characterization and mechanical property and intergranular corrosion measurements. The results reveal that Zn addition can greatly improve the initial age hardening rate and peak aging strengths, the peak hardness, yield and ultimate tensile strengths are 1200 MPa, 313.9 MPa and 358.8 MPa, respectively, but the elongation is only reduced a little bit, and ductile fracture is the main fracture feature as observed by SEM examination of fracture surface. Additionally, the peak aged Al-Mg-Si-Cu alloy added 2.0%Zn also possesses an excellent resistance ability to occur, the intergranular corrosion, the deepest corrosion depth can be reduced from 90 μm for the Zn-free alloy to the value of 40 μm. According to the TEM microstructure characterization, it has been found that Zn addition can greatly improve precipitation rates of phases formed within grains and grain boundaries, Mg-Si precipitates are still the main precipitates formed within the grains, while both Mg-Zn precipitates near the grain boundaries and AlMgSiCuZn precipitates are the main precipitates formed around the grain boundaries under the Zn-added alloy in the peak aging condition. Based on the microstructure evolution and properties, the schematic diagram of forming precipitates within the grains and around the grain boundaries and the intergranular corrosion mechanism of the two Al-Mg-Si-Cu alloys were put forward in this paper.
Key words: Al-Mg-Si-Cu-Zn alloys; aging hardening response; peak aging; intergranular corrosion; modelling; mechanism
