| Surface composite layers reinforced with TiC particles were fabricated by high-energy accelerated electron beam. TiC powders were mixed with MgO/CaO flux powders with varying the flux mixing ratios of 5, 10, 20, and 40 wt.% to process four kinds of TiC/flux mixtures. The TiC/flux mixtures were deposited evenly on a plain carbon steel substrate, on which electron beam was irradiated to fabricate TiC reinforced surface composite layers. The microstructural analysis was conducted using X-ray diffraction and Mo¨ssbauer spectroscopy as well as optical and scanning electron microscopy. The microstructure of the surface composites was composed of surface composite layer, interfacial region, coarse-grained heat affected zone (HAZ), and finegrained HAZ. A few TiC agglomerates and residual micropores were found in the composite layer of the specimen processed without flux because of density difference, but their number was significantly decreased in the specimens processed with a considerable amount of flux. As a result of irradiation, TiC particles were homogeneously dispersed throughout the composite layer of 2.5 ㎜ in thickness, whose hardness was greatly improved. The proper flux mixing ratio was 10˚-20% to obtain excellent surface composite layers containing homogeneously dispersed TiC particles. |
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