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利用高能量的二氧化碳激光束在钢制的工件表面进行了激光熔覆改性处理,制备生成了含有碳氮化钛Ti(C,N)硬质相的复合熔覆层。在热力学分析的基础上,利用电子探针(EPMA)和X射线衍射(XRD),对熔覆层中原位生成的第二相粒子Ti(C,N)的形成机制进行了探究。研究结果表明,先前加入的颗粒状TiN在激光熔覆过程中首先发生了分解反应,而后生成了Ti原子和N原子,新生成的Ti原子再分别与C、N两原子发生化合反应,重新生成了碳化钛TiC和氮化钛TiN两种硬质相。TiC和TiN两者的晶体结构和晶格常数非常相似,它们相互固溶,原位生成了碳氮化钛Ti(C,N)连续固溶体,冷却凝固时新生成的碳氮化钛Ti(C,N)固溶体在熔覆层中以Ti(C_(0.3)N_(0.7))颗粒强化相析出。它们在熔覆层的基体内呈弥散分布,颗粒细小,形状不规则。
A high-energy carbon dioxide laser beam was used to laser-modify the surface of a steel workpiece to prepare a composite cladding layer containing a Ti (C, N) hard phase of titanium carbonitride. Based on the thermodynamic analysis, the formation mechanism of Ti (C, N) formed in situ in the cladding layer was investigated by using electron probe (EPMA) and X-ray diffraction (XRD). The results show that the previously added granular TiN first undergoes decomposition reaction during laser cladding and then Ti and N atoms are generated. The newly formed Ti atoms are recombined with C and N respectively to regenerate The titanium carbide TiC and titanium nitride TiN two hard phases. The crystal structures and lattice constants of TiC and TiN are very similar. They are solid solution to each other, and the Ti (C, N) TiC solid solution forms in situ. The newly formed TiC , N) solid solution precipitates in the cladding layer with Ti (C_ (0.3) N_ (0.7)) particle strengthening phase. They are dispersed in the matrix cladding body, small particles, irregular shape.