激光熔覆新型Co-Al-W合金熔覆层的工艺及组织

Process and Microstructure of New Co-Al-W Alloy Cladding Layer by Laser Cladding

为了提高新型Co-Al-W合金熔覆层质量及拓展其应用范围,采用场发射SEM观察、X射线衍射等方法对Co-AlW合金涂层的形貌、组织特征、相组成及显微硬度进行了研究。结果表明,当P=1.6kW,V=360 mm/s时,熔覆层具有最好的形貌、最佳的组织和工艺性能;熔覆层主要是由基本上垂直于结合带的树枝晶和枝间共晶组织组成,树枝晶呈多方向生长;在搭接重熔区,凝固组织有明显的粗化;熔覆层合金主要由fcc的γ-Co基体及其上金属间化合物CoXAl和碳化物,如Cr23C6,Co6W6C共同组成;熔覆层硬度总体上由表面到基体呈现下降趋势,熔覆层最高硬度可达732.9 HV1.0。

In order to improve the quality of new Co-Al-W alloy cladding layer and expand its application range, the morphology, microstructure, phase composition and microhardness of Co-Al-W alloy layer were analyzed by field emission SEM observation and X-ray diffraction. The results show that under the experimental conditions, when P = 1. 6 kW and V= 360 mm/s, the cladding layer has the best morphology, optimum microstructure and process performance. The cladding layer is mainly composed of dendrites and inter-column eutectic structures basically perpendicular to the bonding zone,and the dendrites grow in multiple directions. In the lapped remelting zone, the solidification structure has obvious coarsening, the cladding alloy is mainly consists of fccγCo matrix and the upper intermetallic compounds Cox Al and carbides,such as Cr23C6 and Co6W6C. The hardness of the cladding layer generally show a downward trend from the surface to the substrate, and the maximum hardness of the cladding layer can reach 732. 9 HV1.0.