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Effect of one-step and two-step homogenization treatments on distribution of Al_3Zr dispersoids in commercial AA7150 aluminium alloy

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Transactions of Nonferrous Metals Society of China 2012年第11期22卷 2645-2651页

作者：吕新宇郭二军 paul rometsch 王立娟哈尔滨理工大学材料科学与工程学院哈尔滨150080 东北轻合金有限责任公司哈尔滨150060 ARC Centre of Excellence for Design in Light Metals Department of Materials Engineering Monash University Melbourne VIC 3800 Australia

Semi-quantitative electron probe microanalysis （EPMA） mapping, scanning electron microscopy （SEM） and transmission electron microscopy （TEM） were employed to study the effect of one-step and two-step treatments on the Zr distribution and Al3Zr dispersoid characteristics in as-cast commercial AA7150 aluminum alloy. It is shown that the Zr concentration in the dendrite centre regions is higher than that near the dendrite edges in the as-cast condition, and that homogenization at 460 °C for 20 h is insufficient to remove these concentration gradients. After homogenizing at 460-480 °C, a high number density of larger dispersoids can be observed in dendrite centre regions but not near dendrite edges. Furthermore, the dispersoid size increases with increasing the temperature during both one-step and two-step homogenization treatments.

关键词： 7xxx alloy AA7150 alloy homogenization recrystallization Al3Zr dispersoids concentration gradient

Effect of platform temperature on microstructure and corrosion resistance of selective laser melted Al-Mg-Sc alloy plate

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Journal of Central South University 2022年第3期29卷 999-1014页

作者： LI Meng-jia LIAN Juan CAO Ling-fei SHI Yun-jia ZHANG Guo-peng WANG Jie-fang rometsch paul School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China Key Laboratory of Material Physics of Ministry of Education School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Arvida Research and Development Center Rio Tinto AluminumQC G7S 4K8Canada Department of Materials Science and Engineering Monash UniversityClaytonVIC 3800Australia

The Al-3.40Mg-1.08Sc alloy plates were manufactured by selective laser melting(SLM) at platform temperatures of 35 ℃ and 200 ℃, respectively, and the corrosion performance of them was studied along height direction. The results show that the corrosion resistance of the alloy plate built at platform temperature of 35 ℃ along height direction is basically the same due to a uniform microstructure;While the corrosion resistance of the alloy plate built at platform temperature of 200 ℃ along height direction is different. The evolution of microstructure and the distribution of secondary phases are investigated, and the results show that the Cu-rich phases in alloy play a key role on corrosion performance. At higher platform temperature, the cooling rate is relative slow and a certain degree of in situ ageing leads to the significantly different distribution of Cu-rich phases along grain boundary. Specimens built at the platform temperature of 200 ℃ are inclined to locate at the crossed grain boundary, rather than continuous segregation of Cu-rich phases along grain boundary that is built at platform temperature of 35 ℃. Therefore, the corrosion resistance of Al-3.40Mg-1.08Sc alloy plate manufactured at platform temperature of 200 ℃ is higher, and presents a gradually decreasing trend along height direction.

关键词： selective laser melting aluminum alloys microstructure corrosion resistance platform temperature

Heat treatment of 7xxx series aluminium alloys—Some recent developments

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Transactions of Nonferrous Metals Society of China 2014年第7期24卷 2003-2017页

作者： paul A.rometsch Yong ZHANG Steven KNIGHT Department of Materials Engineering Monash University

The 7xxx series alloys are heat treatable wrought aluminium alloys based on the Al-Zn-Mg（-Cu） system. They are widely used in high-performance structural aerospace and transportation applications. Apart from compositional, casting and thermo-mechanical processing effects, the balance of properties is also significantly influenced by the way in which the materials are heat-treated. This paper describes the effects of homogenisation, solution treatment, quenching and ageing treatments on the evolution of the microstructure and properties of some important medium to high-strength 7xxx alloys. With a focus on recent work at Monash University, where the whole processing route from homogenisation to final ageing has been studied for thick plate products, it is reported how microstructural features such as dispersoids, coarse constituent particles, fine-scale precipitates, grain structure and grain boundary characteristics can be controlled by heat treatment to achieve improved microstructure-property combinations. In particular, the paper presents methods for dissolving unwanted coarse constituent particles by controlled high- temperature treatments, quench sensitivity evaluations based on a systematic study of continuous cooling precipitation behaviour, and ageing investigations of one-, two- and three-step ageing treatments using experimental and modelling approaches, in each case, the effects on both the microstructure and the resulting properties are discussed.

关键词： 7xxx aluminium alloys Al-Zn-Mg-Cu homogenisation solution treatment quenching retrogression and re-ageing strength corrosion