ABSTRACT In this research, the role of Si on the solidification behaviour of NiAl cladding produced by the GTAW process was studied. NiAl and Ni2AlSi compounds were synthesised by mechanical alloying. The produced powders were cladded on the surface of CK45 steel using the GTAW process. Phase evolutions, microstructural changes and fractography of the produced powders as well as the cladded layers were characterised by X-ray diffraction, optical microscopy and scanning electron microscopy methods. After cladding of Ni2AlSi powder mixture, in the first pass of this coating, only NiAl phase and in the second pass, only (Ni,Si)Al intermetallic compounds were formed. For ternary coating, a narrow area including cellular solidification mode was seen at fusion boundary which transformed to equiaxed dendritic solidification mode. Fractography analysis of the claddings revealed that by the addition of Si into NiAl lattice, brittle fracture changed to more ductile fracture with ‘eggcrate-type’ appearance, indicating solidification cracking.

中文翻译：

---

Si 对 GTAW 工艺生产的 NiAl 金属间化合物熔覆层凝固行为的作用

摘要 在这项研究中，研究了硅对通过 GTAW 工艺生产的 NiAl 包覆层凝固行为的作用。NiAl和Ni2AlSi化合物通过机械合金化合成。使用 GTAW 工艺将生产的粉末包覆在 CK45 钢的表面。通过 X 射线衍射、光学显微镜和扫描电子显微镜方法对所生产的粉末以及包覆层的相演变、微观结构变化和断口进行表征。Ni2AlSi 粉末混合物包覆后，在该涂层的第一道次中，仅形成 NiAl 相，而在第二道次中，仅形成 (Ni,Si)Al 金属间化合物。对于三元涂层，在熔合边界处看到一个包括细胞凝固模式的狭窄区域，该区域转变为等轴枝晶凝固模式。