Effect of low-frequency electromagnetic field on the as-cast microstructure of a new super high strength aluminum alloy by horizontal continuous casting
The super high strength aluminum alloy ingots with 100 mm in diameter were cast by the process of low-frequency electromagnetic horizontal continuous casting (LFEHC) and the effect of electromagnet ic field on the as-cast microstructure was studied. Results show that microstructure of the sample prepared by the LFEHC process was greatly refined. Microstructures at the border and the center of the ingots were fine, uniform and rosette-shaped. Electromagnetic frequency plays a key role in microstructure refining. Fine and uniform microstructures can be obtained with optimal electromagnetic frequency. In this experiment, under a frequency of 30 Hz the microstructure was the finest and the most uniform.
Present research and developing trends of ultra high strength aluminum alloys
Possessing high strength and toughness, ultra high strength aluminum alloy is a kind of structural material with light weight and high strength, which can be applied widely in the aviation and aerospace fields. Based on a tremendous amount of data and some experiments by the researching group, this paper introduces the development and applications of ultra high strength aluminum alloys, and discusses the addition, existential form and functioning mechanism of such compositions as Zn, Mg, Cu and Zr. Comparing and analyzing a number of data, the thesis discusses the microstructural mode corresponding to the best properties. Additionally, three main aging treatments and two successful stress corrosion resistance models are also reviewed in this paper. In the end, aiming at the existing problems of the present study, the paper puts some suggestions for the future exploration of the high strength aluminum alloys.
SR topography of plastically deformed Fe-Si bicrystals - observation in situ and post mortem
SR reflection topography was applied to study the interaction of slip dislocations with the grain boundaries in Fe-4at%Si bicrystals deformed by compression. Three experimental settings with either a white or monochromatic beam were used and the corresponding orientation contrast analysed. Dislocation transmission through the grain boundary was observed in bicrystals with favourable geometry of the slip systems.