Interdiffusion kinetics in the Mo5SiB2 (T2) phase
Interdiffusion kinetics in the Mo5SiB2 (T2) phase
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DOI：
10.1007/bf02736562
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发表时间：
2006-12
影响因子：
1.4
通讯作者：
Sungtae Kim;J. Perepezko
中科院分区：
文献类型：
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作者：
Sungtae Kim;J. Perepezko
基于Mo 2B和Mo 5Si 3的扩散偶被用来确定T2相发展的扩散动力学和控制动力学的相对扩散系数。在1600 °C以上对Mo_2B/Mo_5Si_3扩散偶进行退火，得到了Mo_2B/T_2/Mo_3Si/Mo_5Si_3的初始扩散路径序列，随后通过长期退火使Mo_3Si相收缩而转变为Mo_2B/T_2/（Mo_3Si + Mo_5Si_3）/Mo_5Si_3。T2相由Mo 2 B形成，在T2相生长过程中，Si和B原子的运动受Si浓度梯度的驱动。T2相中Si互扩散的激活能为355 kJ/mole，而Mo/Si和MoSi 2/T2扩散偶中Mo 5Si 3的激活能约为300 kJ/mole。与Mo 5Si 3相比，较大的激活能是Si在T2相中较低的扩散率的主要原因。在T2相中的相对缓慢的扩散与T2相显微组织所表现出的增强的抗蠕变性一致。
Diffusion couples based on Mo2B and Mo5Si3were used to determine the diffusion kinetics of T2phase development and the relative diffusivities controlling the kinetics. Annealing the Mo2B/Mo5Si3diffusion couple above 1600 °C yielded an initial diffusion path sequence of Mo2B/T2/Mo3Si/Mo5Si3, which was subsequently transformed to Mo2B/T2/(Mo3Si+Mo5Si3)/Mo5Si3by shrinkage of the Mo3Si phase upon long-term annealing. The T2phase developed from Mo2B and during the growth of the T2phase, Si and B atom movements were driven by the Si concentration gradient. The activation energy for Si interdiffusion in the T2phase was evaluated to be 355 kJ/mole compared with about 300 kJ/mole for Mo5Si3in both Mo/Si and MoSi2/T2diffusion couples. The larger activation energy is mainly responsible for the 103lower diffusivity for Si in the T2phase compared with Mo5Si3. The relatively slow diffusion in the T2phase is consistent with the enhanced creep resistance exhibited by T2phase microstructures.