Correlations between microstructure and room temperature tensile behavior of a duplex TNB alloy for systematically heat treated samples
Correlations between microstructure and room temperature tensile behavior of a duplex TNB alloy for systematically heat treated samples
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DOI：
10.1016/j.msea.2015.03.041
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发表时间：
2015-05
期刊：
影响因子：
6.4
通讯作者：
M. R. Kabir;M. Bartsch;L. Chernova;K. Kelm;J. Wischek
中科院分区：
文献类型：
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作者：
M. R. Kabir;M. Bartsch;L. Chernova;K. Kelm;J. Wischek
TiAl合金的机械性能对其固有的微观结构非常敏感。为了深入了解微观结构对机械性能的影响，对双相 TNB（含铌 TiAl）合金进行了研究。为了改变这种合金的微观结构，我们在八个不同的最高温度下进行了控制热处理 (HT)，温度范围从 1230°C 到 1300°C，温度增量为 10°C。这一系列的退火过程导致了双相微观结构，球状晶粒和层状团落的比例逐渐变化，保持整体化学成分不变。在机械测试之前和之后使用 SEM 和 TEM 对每个样品的微观结构进行表征，以将形态和微观结构特征与拉伸性能相关联。这些结果的定量数据分析揭示了双相微观结构的演变如何影响室温拉伸性能：即弹性刚度、室温延展性、加工硬化、断裂应力和断裂应变。根据从拉伸试验结果和断裂表面研究中了解的变形机制，对结果进行了讨论。根据观察到的微观结构和性能之间的相关性，可以预测相关性能的球状和层状微观结构的优化星座。此外，还可以定义目标性能所需的热处理窗口。
The mechanical properties of TiAl alloys are very sensitive to the inherent microstructure. For an in-depth understanding of microstructural influences on mechanical properties a duplex type TNB (Nb-containing TiAl) alloy has been investigated. For varying the microstructure of this alloy controlled heat treatments (HT) have been performed with eight distinct maximum temperatures, ranging from 1230 °C to 1300 °C with a 10 °C temperature increment. The series of annealing processes resulted in duplex microstructures with a gradual change of the ratio of globular grains and lamellar colonies, keeping the global chemical composition unchanged. Microstructure of each sample was characterized using SEM and TEM before and after mechanical testing to correlate the morphology and microstructure features to the tensile properties. Quantitative data analysis from these results revealed how the evolution of duplex microstructures influences the room temperature tensile properties:i.e.the elastic stiffness, room temperature ductility, work hardening, fracture stress, and fracture strain. The results are discussed with respect to deformation mechanisms as understood from the tensile test results and fracture surface investigations. From the observed correlations between microstructure and properties an optimized constellation of globular and lamellar microstructure for relevant properties can be predicted. Furthermore, the required heat-treatment window for properties targeted can be defined.