Fabrication of TiC-reinforced ferrous surface composite layers using accelerated electron beam irradiation

摘要

Surface composite layers reinforced with TiCparticles were fabricated by high-energy accelerated electronbeam. TiC powders were mixed with MgO/CaO flux powderswith varying the flux mixing ratios of 5, 10,20, and 40 wt.% toprocess four kinds of TiC/flux mixtures. The TiC/flux mixtureswere deposited evenly on a plain carbon steel substrate, on whichelectron beam was irradiated to fabricate TiC reinforced surfacecomposite layers. The microstructural analysis was conductedusing X-ray diffraction and Mossbauer spectroscopy as well asoptical and scanning electron microscopy. The microstructure ofthe surface composites was composed of surface composite layer,interfacial region, coarse-grained heat affected zone (HAZ), andfinegrained HAZ. A few TiC agglomerates and residualmicropores were found in the composite layer of the specimenprocessed without flux because of density difference, but theirnumber was significantly decreased in the specimens processedwith a considerable amount of flux. As a result of irradiation, TiCparticles were homogeneously dispersed throughout the compositelayer of 2.5 mm in thickness, whose hardness was greatlyimproved. The proper flux mixing ratio was 1O°~2O% to obtainexcellent surface composite layers containing homogeneouslydispersed TiC particles.