The work is devoted to the study of the microstructure and mechanical properties of the nickel base superalloy Inconel 718 manufactured by selective laser melting (SLM). Multiple cycles of heating and cooling during SLM led to the formation of a complex microheterogeneous microstructure. The microstructure of the superalloy manufactured by SLM consisted of elongated γ grains with a transversal size of 10 -100 μm and a longitudinal size of 50 -300 μm, which in its turn consisted of columnar and equiaxed subgrains. Stable and metastable precipitates of the δ-Ni 3 Nb and γ''-Ni 3 Nb phases, carbides and probably oxides, were detected along the subboundaries. The standard heat treatment of the superalloy manufactured by SLM resulted in a partial dissolution of the δ phase and the metastable γ'' phase during solid solution treatment and precipitation of the dispersed metastable γ'' phase during ageing. The microstructure characterization performed by electron backscatter diffraction technique (EBSD analysis) revealed that the size and elongated form of the γ grains was not changed after the heat treatment, the size of the subgrains slightly increased, the fraction of low-angle boundaries (subboundaries) decreased, and the fraction of high-angle grain boundaries increased. Tensile tests were carried out at T = 20 -700°C for the superalloy samples subjected to standard heat treatment. The tensile direction was parallel to the building direction. The tensile tests showed that the superalloy manufactured by SLM exceeded the requirements of the AMS 5662 certificate for the superalloy Inconel 718 in a hot forged condition subjected to standard heat treatment.
The problems related with a dichroic type polarization filter plate which is used as a spatial image separator for a non-glasses type stereoscopic display device utilizing a liquid crystal display panel are discussed. The filter plate is consisted of many parallel line filters. Each line filter is directing the light with the same polarization only to its corresponding pixel lines in the display panel. The filter plate is cemented to the display panel, back-illuminated by a halogen lamp through two cross-polarized polarizers in side by side. Two Fresnel lenses located before the filter plate for collimating the illuminating beam and after the liquid crystal dispaly panel for forming the images of two polarizers in front of the liquid crystal display panel as viewing zones are used.
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