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利用辉光等离子表面冶金技术在Nb521合金表面制备了Mo合金层,研究了渗Mo过程中的扩散行为:主要分析了渗金属温度,保温时间对渗层厚度和扩散速率的影响。采用扫描电子显微镜(SEM)观察渗层表面、截面形貌,X射线能谱仪(EDS)检测渗层界面元素分布。实验结果表明,渗层由扩散层和沉积层组成,且组织致密,颗粒细小,无明显显微裂纹等缺陷,与基体结合良好。温度是影响扩散速率的最主要因素,随着温度的升高,扩散速率逐渐增加,而保温时间对扩散速率的影响不大。最佳工艺下,渗层厚度可达26.5μm,扩散层厚度可达6.89μm,扩散速率可达1.73μm.h-1,Mo元素含量从表面到心部呈梯度分步,在涂层与基体的界面处,钼铌原子发生了不同程度的互扩散。最后依据传统扩散理论计算得到了Mo在不同实验温度下的扩散系数,并拟合得到了离子轰击作用下Mo在Nb521合金中的扩散激活能为292 k.Jmol-1。
The Mo alloy layer was prepared on the surface of Nb521 alloy by glow plasma surface metallurgy. The diffusion behavior during infiltration of Mo was studied. The effects of infiltration metal temperature and holding time on the diffusion layer thickness and diffusion rate were analyzed. Scanning electron microscope (SEM) was used to observe the surface, cross-sectional morphology and X-ray energy dispersive spectrometer (EDS). The experimental results show that the diffusion layer is composed of diffusion layer and sedimentary layer, and has the advantages of compact structure, small particle size, no obvious micro-cracks and other defects, and has good bonding with the substrate. Temperature is the most important factor affecting the diffusion rate. With the increase of temperature, the diffusion rate increases gradually, while the holding time has little effect on the diffusion rate. Under optimum conditions, the thickness of diffusion layer can reach 26.5μm, the thickness of diffusion layer can reach 6.89μm and the diffusion rate can reach 1.73μm.h-1. The content of Mo element is graded stepwise from the surface to the heart, Interface, molybdenum and niobium atoms have varying degrees of mutual diffusion. Finally, according to the traditional diffusion theory, the diffusion coefficient of Mo at different experimental temperature was calculated and the diffusion activation energy of Mo in Nb521 alloy was obtained by ion bombardment as 292 kJmol-1.