Papers by Keyword: Micro-Crystal

Abstract: In this study, the digital image correlation method(with Newton-Raphson iteration method) is used to measure the in-plane deformation of poly-crystal aluminum. When the specimen is exerted a tensile load, the strain distribution of the specimen surface will be inhomogeneous. The micro-deformation of the poly-crystal aluminum is studied under a SEM(scanning electron microscope), a series of images of the micro crystal are captured during the loading process. By using digital image correlation to analyze the images, the displacement and strain of a micro-crystal are obtained, which provide important data for further analysis of the inhomogeneous properties of the poly-crystal aluminum.

Abstract: A novel technique has been developed to prepare micro-/nano-crystal aluminized ODS coatings on stainless steel and nickel-base superalloy. In this technique, the pack aluminizing is combined with the repeated ball impact. Pure Al powder is mixed with 1wt% Y2O3 powder by ball milling. The ultrafine Y2O3 powder is well dispersed in Al particles. The modified Al particles are welded to the surface of metals by ball impact, causing the refinement of coarse grains and acceleration of atomic diffusion. Micro-/nano-crystal alloy layer with Y2O3 grows outward at a much low temperature (below 600°C) and in short treatment duration, compared with conventional pack aluminizing. The effects of processing temperature and duration on formation of the coatings have been analyzed. The microstructure of the coatings is studied using the methods of SEM, AMF, EDS, XRF and XRD. The results indicate that the aluminized ODS coatings appear to be dense, homogeneous, micro-/nano-crystal structure, and consist mainly of Al-rich phases, such as Fe2Al5, FeAl3 NiAl3 and7 CrAl5. High temperature oxidation tests show that the coatings enhance the oxidation resistance.