In situ observations of lattice expansion and transformation rates of α and β phases in Ti-6Al-4V
In situ observations of lattice expansion and transformation rates of α and β phases in Ti-6Al-4V
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DOI：
10.1016/j.msea.2004.08.084
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发表时间：
2005-01-25
期刊：
影响因子：
6.4
通讯作者：
Specht, ED
中科院分区：
文献类型：
--
作者：
Elmer, JW;Palmer, TA;Specht, ED
利用同步辐射对 Ti-6Al-4V 样品进行原位 X 射线衍射实验，直接观察加热过程中的 α→β 相变。这些实验是在先进光子源 (APS) 上进行的，使用 30 keV 同步加速器 X 射线束来监测 α 相和 β 相的变化，作为不同加热速率下加热时间的函数。将结果与相分数与温度的计算热力学预测进行比较，提供有关 Ti-6Al-4V 中 α→β 转变动力学的信息。测量的转变速率与扩散控制生长机制一致，即 V 在 β-Ti 相中的扩散控制速率。根据X射线衍射数据，实时测量α相和β相晶格参数。在转变过程中，两相晶格参数的变化观察到显着差异。这些变化被认为是由于V的分配及其对β相晶格参数的强烈影响。在500至600℃的温度范围内加热期间，进一步观察到β相晶格参数的意外收缩。这种收缩的起源很可能与两相不同的热膨胀行为产生的残余应力的退火有关。由 Elsevier B.V. 出版
In situ X-ray diffraction experiments using synchrotron radiation were performed on Ti-6Al-4V samples to directly observe the alpha --> beta phase transformation during heating. These experiments were conducted at the Advanced Photon Source (APS) using a 30 keV synchrotron X-ray beam to monitor changes in the alpha and beta phases as a function of heating time under different heating rates. The results were compared to computational thermodynamic predictions of the phase fractions versus temperature, providing information about the kinetics of the alpha --> beta transformation in Ti-6Al-4V. The measured transformation rates were shown to be consistent with a diffusion-controlled growth mechanism, whereby diffusion of V in the beta-Ti phase controls the rate. Based on the X-ray diffraction data, real time measurements of the alpha and beta phase lattice parameters were made. Dramatic differences were observed in the changes of the lattice parameters of the two phases during the transformation. These changes are believed to be due to the partitioning of V and its strong effect on the lattice parameter of the beta phase. An unexpected contraction of the lattice parameter of the beta phase was further observed during heating in the temperature range between 500 and 600degreesC. The origin of this contraction is most likely related to the annealing of residual stresses created by the different thermal expansion behaviors of the two phases. Published by Elsevier B.V.