Microscale mechanical properties of ultra-high-strength polysynthetic TiAl-Ti 3 Al single crystals
Microscale mechanical properties of ultra-high-strength polysynthetic TiAl-Ti 3 Al single crystals
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DOI：
10.1016/j.msea.2018.06.076
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发表时间：
2018-08
期刊：
影响因子：
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通讯作者：
D.P. Wang;Z. Qi;H.T. Zhang;G. Chen;Y. Lu;B. Sun;C. Liu
中科院分区：
文献类型：
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作者：
D.P. Wang;Z. Qi;H.T. Zhang;G. Chen;Y. Lu;B. Sun;C. Liu
最近发展起来的TiAl-Ti3Al金属间化合物多晶具有优异的力学性能，这使得人们对其组成相的微观力学性能进行了深入的研究。然而，由于测量需要高横向分辨率和卓越的机械灵敏度，因此很难获得纳米级各个相的机械性能。在这里，我们使用扫描纳米压头和纳米DMA的方法，报告了它们各自相在纳米尺度上的模数图和纳米压痕硬度的临界数据。此外，在聚焦离子束加工的纳米管柱上进行了原位压痕，获得了各相的屈服强度和塑性。对于0°片层取向的样品，α2-Ti3Al和γ-TiAl金属间化合物相的弹性模量值分别约为140和180 Gpa，高于45°片层取向样品的弹性模量值约为120和160 Gpa。微观尺度和宏观尺度之间的关系可以用Voigt-Reuss近似来描述。更重要的是，AFM结果表明，具有0°片层取向的单晶的塑性变形更加均匀，这是因为它们的组织更均匀，两相之间的硬度差异较小。从微观结构和微观力学性能的角度，我们的研究结果对新型TiAl基单晶作为结构材料的应用和设计具有一定的参考价值。
The excellent mechanical properties of recently developed polysynthetic TiAl-Ti3Al intermetallic single crystals lead to a high motivation to explore the micro-mechanical properties of their constitutional phases. However, the mechanical properties of the individual phases at the nanoscale are hard to obtain since the measurement requires a high lateral resolution and superior mechanical sensitivity. Here, using a method of scanning nanoindenter together with nanoDMA, we report the critical data of modulus maps and the nanoindentation hardness of their individual phases at the nanoscale. Furthermore, the yield strength and plasticity of the individual phases were obtained using anin situnanoindentation on the focused ion beam machined nanopillars. The value of elastic modulus is measured to be about 140 and 180 GPa, respectively forα2-Ti3Al andγ-TiAl intermetallic phases, for samples with 0° lamellar orientation, which is higher than the value of about 120 and 160 GPa for the same phases in samples with 45° lamellar orientation. The relationship between the microscale and macroscale modulus can be described using the Voigt-Reuss approximation. More importantly, AFM results show that the plastic deformation is more uniform for the single crystals with 0° lamellar orientation, since they have more homogeneous microstructure and smaller difference in the hardness between the two phases. Our findings are useful to promote the applications and design of new TiAl-based single crystals as structural materials, from the perspective of the microstructure and micro-mechanical properties.