中文摘要：

通过脉冲激光熔覆技术在低碳钢表面上制备高致密铁基非晶合金涂层,研究了不同脉冲频率对涂层组织与性能的影响。利用光学显微镜（OM）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）、显微硬度仪、电化学工作站等测试方法分别分析了涂层成形、组织特征、显微硬度与耐腐蚀性能。研究结果表明,涂层主要由非晶组成,随脉冲频率降低,涂层厚度减小,稀释率降低,非晶化程度升高;当脉冲频率为1.0 Hz时,涂层稀释率显著降低50%,且未析出明显结晶相。随脉冲频率降低,熔合区宽度减小,柱状晶沿外延生长趋势变小,涂层显微硬度表现为先增加后减小,耐腐蚀性能先明显增强后减弱,且在3.5%NaCl溶液中耐腐蚀性能明显优于316L不锈钢。当脉冲频率为1.0 Hz时,涂层结构致密,平均显微硬度最高,达HV 1315,约为基材的9倍,涂层自腐蚀电流密度及钝化电流密度最低,分别为1.81×10（-8）,7.10×10（-7）A·cm（-2）,耐蚀性能表现最强。

英文摘要：

High-density Fe-based alloy amorphous coating was fabricated on the surface of mild steel by laser cladding,and then the effect of pulse frequency on the microstructure and properties of the coatings were studied. The formation,microstructure characterization,microhardness and corrosion resistance of the coatings were investigated by optical microscope（ OM）,X-ray diffraction（ XRD）,scanning electron microscopy（ SEM）,microhardness tester and electrochemical workstation,respectively. The results showed that the coatings were mainly constituted by amorphous materials. With the decrease of pulse frequency,the thickness of the coatings decreased,and the dilution rate also got lower,and the amorphization in coating happened easily. Moreover,the dilution rate dramatically went down by about 50% and no distinct crystallization phase was observed when frequency was 1. 0 Hz. With the decrease of pulse frequency,fusion zone width increased and the tendency of columnar crystals along the epitaxial growth got low,in addition the microhardness increased firstly and then decreased and the corrosion resistance firstly obviously got strong and then vulnerable,which had more excellent corrosion resistance than 316 L stainless steel in the 3. 5% NaCl solution. When frequency was 1. 0 Hz,there were compact structure of the coating,and average microhardness exceeded HV 1315,which was about 9 times as much as the substrate. When the low corrosion current density and passive current density were about 1. 81 × 10（-8）,7. 10 ×10（-7）A·cm（-2）,the corrosion resistance was best.