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Cheng X.-H.,Sichuan University | Mao J.,Sichuan University | Che Y.,Guizhou Aluminum Materials Engineering Research Center | Zhang Z.-K.,Guizhou Aluminum Materials Engineering Research Center
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

Microstructure, the change of mechanical properties before and after corrosion and the degree of intergranular corrosion of 211Z casting aluminum and 211Z hot-extruded aluminum after peak aging treated were comparison investigated. The results show that the grade of intergranular corrosion of casting specimen is 4 and that of hot-extruded specimen is 3. This indicates that, the intergranular corrosion resistance of 211Z alloy can be improved to some extent by extrusion-heat treatment process. Moreover, the decline degree of mechanical property of hot-extruded specimen is less than that of casting specimen. The main reason is that, after hot extrusion, the precipitates in grain boundary become dispersed and the precipitation free zones (PFZ) is shorted and narrowed, which destroy the continuous corrosion pathway along PFZ. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved. Source


Wu X.,Sichuan University | Mao J.,Sichuan University | Zhang Z.,Guizhou Aluminum Materials Engineering Research Center | Che Y.,Guizhou Aluminum Materials Engineering Research Center
Surface and Coatings Technology | Year: 2015

Ni-P-TiO2 nanocomposite coatings on 211Z Al alloy substrate were prepared by electroless deposition through adding TiO2 sol into conventional Ni-P electroless plating solution, and the Ni-P coatings on 211Z Al alloy were also prepared as a comparison. The properties of 211Z Al alloy with Ni-P and Ni-P-TiO2 deposits in as-plated and heat-treated states were investigated. It was found that, after heat treatment at 400°C for 1h, the microhardness of 211Z Al alloy with Ni-P coatings increased from 608HV to 929HV, while that with Ni-P-TiO2 nanocomposite coatings greatly increased from 685HV to 1325HV at the same condition. The far higher improvement in the microhardness of heat-treated Ni-P-TiO2 nanocomposite coatings was attributed to the formation of more Ni3P hard phase, finer spherical nodular shaped grain size and the existence of more Ni atoms arranged along (111) close-packed planes. In the salty environment, 211Z Al alloy substrate with Ni-P-TiO2 coatings exhibited higher corrosion resistance than pure 211Z Al alloy substrate. © 2015 Elsevier B.V. Source


Mou G.,Sichuan University | Che Y.,Guizhou Aluminum Materials Engineering Research Center | Jiang Y.,Sichuan University | Zhang Z.,Guizhou Aluminum Materials Engineering Research Center | Mao J.,Sichuan University
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2015

The water quenching hardening property of 211Z aluminum alloy was investigated by end-quenching instrument, electrical conductivity meter, differential scanning calorimetry, transmission electron microscopy and numerical simulation method. The results show that the supersaturation degree as well as the hardness after aging treatment of samples treated by water quenching below 40℃ are higher than those of samples treated by higher temperature (50~60℃) water quenching. But, the influence of water temperature on quenching depth is reverse. Hardness of samples after aging treatment is influenced by average cooling rate during quench sensitivity temperature interval (140~380℃). When the average cooling rate exceeds a critical value, the hardness remains the maximum and unchanged. However, the hardness increases with the increase of average cooling rate when it is less than the critical value. © 2015, Science Press. All right reserved. Source

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