Kunčická Lenka, Jambor Michal, Král Petr
Institute of Physics of Materials, Czech Academy of Sciences, Žižkova 22, 616 00 Brno, Czech Republic.
Materials (Basel). 2023 Mar 29;16(7):2738. doi: 10.3390/ma16072738.
By optimizing the fabrication method, copper components featuring (typically contradicting) advantageous electric conductivity and favorable mechanical properties can be acquired. In this study, we subjected conventional electroconductive copper to a single revolution of high pressure torsion (HPT) at room temperature (RT), searched for the conditions which would yield comparable structure characteristics (grain size) when deformed at a cryogenic temperature, and finally compared the mechanical and electric behaviors to assess specific differences and correlate them with the (sub)structural development. 180° revolution of cryo-HPT imparted structure refinement comparable to 360° revolution of room temperature HPT, i.e., the average grain size at the periphery of both the specimens was ~7 µm. The 360° RT HPT specimen exhibited preferential (111)||SD (shear direction) texture fiber in all the examined regions, whereas the 180° cryo-HPT specimen exhibited more or less randomly oriented grains of equiaxed shapes featuring substantial substructure development of a relatively homogeneous character and massive occurrence of (nano)twins. These structural features resulted in the increase in microhardness to the average value of 118.2 HV0.2 and the increase in the electric conductivity to 59.66 MS·m (compared to 105 HV0.2 and 59.14 MS·m acquired for the 360° RT HPT specimen). The deformation under the cryogenic conditions also imparted higher homogeneity of microhardness distribution when compared to RT processing.
通过优化制造方法，可以获得具有（通常相互矛盾的）有利电导率和良好机械性能的铜部件。在本研究中，我们在室温（RT）下对传统导电铜进行了单次高压扭转（HPT），寻找在低温下变形时能产生可比结构特征（晶粒尺寸）的条件，最后比较机械和电学行为以评估具体差异并将它们与（亚）结构发展相关联。低温HPT旋转180°所带来的组织细化程度与室温HPT旋转360°相当，即两个试样边缘处的平均晶粒尺寸均约为7 µm。360°室温HPT试样在所有检测区域均呈现出优先的（111）||SD（剪切方向）织构纤维，而180°低温HPT试样呈现出或多或少等轴形状的随机取向晶粒，具有相对均匀特征的大量亚结构发展以及大量（纳米）孪晶的出现。这些结构特征导致显微硬度增加到平均值118.2 HV0.2，电导率增加到59.66 MS·m（相比之下，360°室温HPT试样的显微硬度为105 HV0.2，电导率为59.14 MS·m）。与室温加工相比，低温条件下的变形还使显微硬度分布具有更高的均匀性。
