Metallic Glass Formation Upon Rapid Solidification of Fe60Cr8Nb8B24 (at%) Alloy through LASER Cladding and Remelting

Fe60Cr8Nb8B24 (at%) amorphous powder and ingot were submitted to LASER cladding and remelting process, respectively. Fe-based coatings were produced using different LASER processing parameters and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Vickers microhardness. All coatings obtained by LASER cladding (LC) and layers obtained by LASER surface remelting (LSR) with shorter and median interaction times (scanning speeds of 16.7 and 66.7mm/s), irrespective of overlap value, presented peaks of the crystalline phases α-Fe, Fe2B and the FeNbB intermetallic. In addition, layers obtained by LSR with shorter interaction time (150mm/s), in general, presented only peaks of the α-Fe and Fe2B phases, except that produced with overlap value of 20%, more amorphous. SEM results showed that, regardless of LASER process, the coatings presented cracks, some pores and FeNbB intermetallic phase. All coatings obtained by LC and that obtained with shorter interaction time, by LSR, showed a Vickers microhardness, 1086 to 1329HV and 2161 to 2294HV, respectively, significantly higher than the substrates, AISI steel: 170HV and Fe-Cr-Nb-B: 1921HV.

原子百分比为Fe₆₀Cr₈Nb₈B₂₄的非晶粉末与铸锭分别接受了激光熔覆与激光重熔工艺处理。采用不同激光工艺参数制备铁基涂层，并通过扫描电子显微镜（scanning electron microscopy, SEM）、X射线衍射（X-ray diffraction, XRD）以及维氏显微硬度测试对其进行表征。所有通过激光熔覆（Laser cladding, LC）制备的涂层，以及采用较短与中等交互作用时间（扫描速度分别为16.7mm/s与66.7mm/s）的激光表面重熔（Laser surface remelting, LSR）制备的层状结构，无论搭接率如何，均出现了α-Fe、Fe₂B以及FeNbB金属间化合物的晶相衍射峰。此外，采用较短交互作用时间（扫描速度150mm/s）的激光表面重熔制备的层状结构，通常仅出现α-Fe与Fe₂B相的衍射峰；唯有搭接率为20%的试样例外，其非晶相占比更高。扫描电子显微镜测试结果表明，无论采用何种激光工艺，所制备的涂层均存在裂纹、少量孔隙以及FeNbB金属间相。所有通过激光熔覆制备的涂层，以及通过激光表面重熔制备的短交互作用时间试样，其维氏显微硬度分别为1086~1329HV与2161~2294HV，显著高于基体材料：AISI钢（170HV）与Fe-Cr-Nb-B合金（1921HV）。