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Ti Based Nanocomposites Prepared by High Energy Ball Millng and Selective Laser Melting Behavior

Author: LiChuang
Tutor: ShenYiFu;GuDongDong
School: Nanjing University of Aeronautics and Astronautics
Course: Materials Science
Keywords: High energy ball milling Nanocomposite powder Ti Situ reinforced Selective Laser Melting Microstructure Formation Mechanism
CLC: TB383.1
Type: Master's thesis
Year: 2011
Downloads: 45
Quote: 0
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Abstract


Metal matrix nanocomposites enhanced phase added plus particle reinforced situ enhancement can be divided into two kinds. Nano enhanced relative to the uniform distribution and prevent nanostructures roughened metal matrix nanocomposites preparation performance key. In this paper, the planetary mill equipment, high-energy ball milling micron TiC / Ti and SiC / Ti powder system, prepared nano-the TiC enhanced amorphous Ti matrix composite powder and nano TiC in situ enhanced Ti 5 Si < sub> 3 matrix composite powder and success of TiC / Ti and TiC / Ti , 5 Si 3 nano-composite specimens were prepared by selective laser melting process. TiC / Ti powder mixture with milling time increased to 15 h amorphous transition induced by high energy ball milling Ti severe plastic deformation occurs, resulting in a large number of lattice defects, resulting in Ti. Experienced two serious refinement phase composite powder particles in milling to 10 h and 20 h. The final nanoparticles TiC reinforced the amorphous Ti matrix composite powders, nanoscale TiC Ti substrate evenly distributed. In situ preparation of TiC / Ti 5 Si 3 the nanocomposite powder process, SiC 25 h energy ball milling gradual decomposition of Ti in a relatively short period of time (10 h) fully participate in the reaction. TiC / Ti 5 Si 3 nanocomposite powder structure goes through the the primary refinement - coarsening - secondary refinement process. Refinement process of the composite powder particles stratified broken into the main mechanism. High energy ball milling 25h, the nano-particles in TiC in Ti5Si3 substrate evenly dispersed. Selective laser melting experiments, TiC / Ti nanocomposite powders were successfully prepared TiCx enhanced Ti-based nanocomposites specimens. The energy density of the laser line η was 1100 J / m, the molded specimen is dense up to 95.6%. Enhancers TiCx lamellar nanostructures and an average thickness of 54 nm, and evenly distributed in the Ti substrate. Of TiCx lamellar nanostructure since the TiC core began when formed, its growth by laser melting pool unique \flake nanostructure growth. Selective Laser Melting SiC / Ti composite powder in situ TiC / Ti 5 Si 3 composite specimens were prepared. When the energy density of the laser line η was 800 J / m, the SLM test piece remains good solidification of tissue continuity and uniformity, density of 94.6%. Gauss distribution center and the edge of the laser molten pool will form a significant temperature gradient in chemical concentration gradient, and thus generate the pool surface tension gradient, it is prone to constitutional undercooling, resulting in situ formation of TiC laser energy density was presented sticks crystalline morphology. Discuss the the laser fast fusing process TiC / Ti 5 Si 3 composite formation mechanism.

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