Wang Shuaizhuo, Yan Haotian, Zhang Dongmei, Hu Jiajun, Li Yusheng
National Key Laboratory of Transient Physics, Nanjing University of Science and Technology, Nanjing 210094, China.
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Materials (Basel). 2023 Nov 6;16(21):7059. doi: 10.3390/ma16217059.
This study investigates the microstructures and deformation mechanism of hetero-structured pure Ti under different high strain rates (500 s, 1000 s, 2000 s). It has been observed that, in samples subjected to deformation, the changes in texture are minimal and the rise in temperature is relatively low. Therefore, the influence of these two factors on the deformation mechanism can be disregarded. As the strain rate increases, the dominance of dislocation slip decreases while deformation twinning becomes more prominent. Notably, at a strain rate of 2000 s, nanoscale twin lamellae are activated within the grain with a size of 500 nm, which is a rarely observed phenomenon in pure Ti. Additionally, martensitic phase transformation has also been identified. In order to establish a correlation between the stress required for twinning and the grain size, a modified Hall-Petch model is proposed, with the obtained value of Ktwin serving as an effective metric for this relationship. These findings greatly enhance our understanding of the mechanical responses of Ti and broaden the potential applications of Ti in dynamic deformation scenarios.
本研究调查了不同高应变速率（500s⁻¹、1000s⁻¹、2000s⁻¹）下异质结构纯钛的微观结构和变形机制。据观察，在经受变形的样品中，织构变化极小，温度升高相对较低。因此，可忽略这两个因素对变形机制的影响。随着应变速率增加，位错滑移的主导地位下降，而形变孪晶变得更加显著。值得注意的是，在2000s⁻¹的应变速率下，尺寸为500nm的晶粒内激活了纳米级孪晶薄片，这在纯钛中是很少观察到的现象。此外，还识别出了马氏体相变。为了建立孪晶所需应力与晶粒尺寸之间的相关性，提出了一个修正的霍尔-佩奇模型，所获得的Ktwin值作为这种关系的有效度量。这些发现极大地增进了我们对钛力学响应的理解，并拓宽了钛在动态变形场景中的潜在应用。
