Formation mechanism of titanium and niobium carbides in hardfacing alloy

• Published in: Rare metals 2017-08, Vol.36 (8), p.640-644
• Main Authors: Yang, Ke, Yang, Kè, Bao, Ye-Feng, Jiang, Yong-Feng
• Format: Article
• Language: English
• Subjects: Alloys; Biomaterials; Carbides; Chemistry and Materials Science; Energy; Epitaxy; Hard surfacing; Hardness; Impact strength; Martensitic transformations; Materials Engineering; Materials Science; Metallic Materials; Microstructure; Nanoscale Science and Technology; Niobium carbide; Nucleation; Physical Chemistry; Scanning electron microscopy; Thermodynamics; Titanium; Titanium carbide; Toughness; Welding; X-ray diffraction; X射线衍射; 光学显微镜; 形成机理; 扫描电子显微镜; 碳化物形成元素; 耐磨堆焊合金; 钛; 铌
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-016-0777-5

The most effective carbide-forming elements titanium and niobium were added into hardfacing alloy.Formation and composition of carbides in the hardfacing alloy were investigated by means of optical microscope（OM）,scanning electron microscope（SEM）,X-ray diffraction（XRD）and energy-dispersive spectrometer（EDS）.Hardness and impact toughness of the hardfacing alloy were measured.The thermodynamics and formation mechanism of carbides were also discussed.It is found that the carbides consist of TiC and NbC which are able to form directly from welding pool during the welding process.The formation mechanism of carbides involves nucleation of TiC followed by epitaxial precipitation of NbC on the surface of TiC.The formation of titanium and niobium carbides can obviously refine the microstructure and deplete the carbon in the matrix.The micros tructure transforms to well-distributed carbides and a tough martensite matrix,contributing to a good combination of high hardness and high toughness in the hardfacing alloy.