Ni Hongjun, Ding Chenchen, Wang Haoyu, Lv Shuaishuai, Wang Xingxing, Liu Yu
School of Mechanical Engineering, Nantong University, Nantong 226019, China.
School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, NSW 2522, Australia.
Materials (Basel). 2023 Jun 29;16(13):4686. doi: 10.3390/ma16134686.
High-pressure torsion (HPT) is an effective severe plastic deformation method to produce ultrafine-grained (UFG) and nanocrystalline (NC) materials. In the past, most studies have focused on the evolutions in the microstructure, texture and mechanical properties of HPT-deformed materials at peripheral regions. The corresponding evolutions at a special area were observed in this study to reveal the potential plastic deformation mechanism for face-centred cubic (FCC) material with high stacking fault energy. A decreasing trend was found in grain size, and the final grain size was less than 1 μm. However, close observation revealed that the general trend could be divided into different sub-stages, in which grain elongation and grain fragmentation were dominant, respectively. Additionally, microhardness demonstrated a non-linear increase with the development of plastic deformation. Finally, the microhardness reached a high level of ~64 HV. At the early stages of HPT, the C component was transformed into a cube component, suggesting the material flows around the shear plane normal (SPN) axis at these stages. However, finally they will be replaced by ideal simple shear orientations.
高压扭转（HPT）是一种制备超细晶粒（UFG）和纳米晶（NC）材料的有效严重塑性变形方法。过去，大多数研究集中在HPT变形材料周边区域的微观结构、织构和力学性能的演变。本研究观察了一个特殊区域的相应演变，以揭示具有高堆垛层错能的面心立方（FCC）材料的潜在塑性变形机制。发现晶粒尺寸呈下降趋势，最终晶粒尺寸小于1μm。然而，仔细观察发现，总体趋势可分为不同的子阶段，其中晶粒伸长和晶粒破碎分别占主导地位。此外，显微硬度随塑性变形的发展呈非线性增加。最后，显微硬度达到了约64 HV的高水平。在HPT的早期阶段，C分量转变为立方分量，表明材料在这些阶段围绕剪切面法线（SPN）轴流动。然而，最终它们将被理想的简单剪切取向所取代。
