Dislocation density and mechanical threshold stress in OFHC copper subjected to SHPB loading and plate impact

作者：Hu, Qiushi; Zhao, Feng^*; Fu, Hua; Li, Kewu; Liu, Fusheng

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2017, 695: 230-238.

DOI：10.1016/j.msea.2017.03.112

• OFHC copper
• SHPB
• Momentum trapping
• X-ray diffraction
• Dislocation density
• Mechanical threshold stress

The dislocation density and mechanical threshold stress (MTS) of oxygen-free high-thermal-conductivity (OFHC) copper loaded at strain rates in the range of 102 to 106 s(-1) were measured. Moderate-strain-rate (10(2) to 10(4) s(-1)) experiments were performed using a Split Hopkinson Pressure Bar (SHPB). A steel collar was placed around each specimen to control the maximum loading strain. High-strain-rate (10(5) to 10(6) s(-1)) experiments were carried out using a 57-mm-bore single-stage gas gun. The radial release effect was eliminated using the momentum trapping technique. The loaded samples were recovered, and the dislocation characteristics and dislocation density were determined by X-ray diffraction profile analysis. The fraction of the screw dislocation was found to decrease with increasing loading strain and strain rate. The dislocation density was found to lie between 1.8 x 10(14) and 2.2 x 10(15) m(-2). Quasi-static reload compression tests were performed on the recovered samples at room temperature. The mechanical threshold stress (or the flow stress at 0 K) was obtained by fitting the reload stress-strain data to the MTS model. The results of analysis of the equivalent strain, mechanical threshold stress, and dislocation density measurements suggest that the relation between the mechanical threshold stress and the dislocation density can be described well by the Taylor relationship.

• 出版日期2017-5-17
• 单位西南交通大学; 中国工程物理研究院流体物理研究所; 中国工程物理研究院