热爆合成-自发熔渗TiC/Fe3Al复合材料的形成机理与磨损性能

来源期刊:中国有色金属学报2018年第7期

论文作者:迟静 李敏 王淑峰 郭延章 吴杰

文章页码:1320 - 1328

关键词:TiC/Fe3Al;热爆合成;自发熔渗;生长机制;磨损

Key words:TiC/Fe3Al; thermal explosion synthesis; pressureless melt infiltration; growth mechanism; wear

摘    要:采用热爆合成-自发熔渗方法快速制备TiC/Fe3Al复合材料,通过相组成和显微组织的演变分析复合材料的形成过程,探讨TiC的生成及长大机制,并对复合材料的滑动摩擦磨损性能进行研究。结果表明:Ti、C热爆合成为TiC多孔压坯,Fe3Al熔体自发渗入压坯孔隙;TiC在熔体中进行溶解-析出,结晶为初生TiC和共晶TiC。进入TiC晶格的Fe优先吸附在{100}晶面上,使其表面能降低,初生TiC形貌由{111}八面体转变为{100}立方体。TiC生长机制为小平面晶的台阶侧向生长,自发熔渗较快的冷却速度使生长台阶增多,形成叠层生长。TiC/Fe3Al复合材料的滑动磨损率为2.7×10-7 g/s,比Fe3Al的下降31.7%。磨损机理研究表明TiC有效抑制了剥层磨损,使复合材料的耐磨损性能提高。

Abstract: TiC/Fe3Al composites were fabricated rapidly by the combination of thermal explosion synthesis and spontaneous melt infiltration. The formation mechanism based on the phase composition and microstructure evolution process, TiC growth mechanism, sliding friction and wear properties of the resultant materials were investigated systematically. The molten Fe3Al spontaneously infiltrates the pores of porous TiC compacts prepared by thermal explosion synthesis using Ti and C powders, resulting in the creation of TiC/Fe3Al composites. The formation of TiC in final products can be attributed to dissolution-precipitation mechanism, i.e., TiC dissolves in Fe3Al melt and decomposes into Ti and C, the latter reacts in the molten pool and precipitates the primary TiC and eutectic TiC during the cooling process. Fe atoms can enter the TiC lattice and be adsorbed preferentially at the {100} crystal plane, giving rise to reduce the surface energy of the {100} plane, so, the morphology of primary TiC changes from {111} octahedron to {100} cube. The TiC growth pattern is lateral growth of facet crystals, tending to grow layer by layer depend on more growth steps provided by the high cooling rate during the fabricate process. The sliding wear rate of TiC/Fe3Al composites is 2.7×10-7 g/s, decreased by 31.7% compared with that of Fe3Al. The wear mechanism indicates that the wear resistance of the composites can be improved noticeably because the addition of TiC may effectively inhibit the delamination wear.

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