激光表面合金化制备TiC/Fe_3Al复合涂层组织及TiC演变规律

Microstructure and TiC Evolution Behavior of TiC/Fe_3Al Composite Coating Fabricated by Laser Surface Alloying

以Al和TiC的混合粉末为原材料对20#钢进行激光表面合金化,制备了TiC增强Fe3Al金属间化合物基体复合涂层。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)等方法分析了涂层的相组成及显微组织结构,通过热力学计算确定了TiC的溶解热力学条件,并探讨了TiC的溶解及析出规律。结果表明:涂层主要组成相为Fe3Al和TiC;激光表面合金化过程中,当温度达到2000K^2200K时,作为粉末原材料的TiC颗粒在Fe-Al合金熔体中开始发生溶解,然后在合金熔池中重新凝固析出,以原位增强颗粒的形式呈网状分布于Fe3Al金属间化合物基体上。

TiC reinforced Fe3Al intermetallic matrix composite coating is fabricated on 0.2% C carbon steel substrate by laser surface alloying with Al-TiC powders blend as the precursor material.The phases composition and microstructure of the composite coating are investigated by X-ray diffractometer（XRD）,scanning electron microscopy（SEM）and energy dispersive spectrometer（EDS）.Through thermodynamic calculating,the dissolution thermodynamic conditions of TiC are confirmed.The dissolution and precipitation behavior of TiC phase are discussed.Results show that the coating mainly consists of Fe3Al and TiC.During the laser surface alloying process,when the temperature reaches 2000 K-2200 K,the TiC powders used as the precursor material begin to dissolve into the Fe-Al alloy melt,as in-situreinforcement particles re-precipitate from the melt and are scattered with a net shape in the Fe3Al matrix.