Shi Qi, Wang Lei, Song Xiu, Liu Yang
The Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
Materials (Basel). 2024 Nov 24;17(23):5745. doi: 10.3390/ma17235745.
The effect of electric-pulse treatment (EPT) on the nucleation behavior of a cold-rolled pure Ti was investigated. The specimens are subjected to EPT and then annealed at 650 °C within 10 min. Both the electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) techniques were used for detailing the microstructural evolution of the specimens at the initial stage of recrystallization processing during annealing. The results show that oriented nucleation occurs in the EPTed specimen. The recrystallized grains form in a similar orientation with the deformed matrix grains, and the oriented nucleation originates from the deformed grains with <0001> poles tilted about 20° away from the normal direction (ND20 grains) in the EPTed specimen. Pyramidal <c + a> dislocations could be extensively activated in ND20 grains, while the activated dislocations were mainly on prismatic planes in the other oriented grains. Because the formation of sub-grains cannot be without the pyramidal <c + a> dislocation, oriented recrystallized grains easily form in the EPTed specimen. It is suggested that the increasing of pyramidal dislocation climbing activity is considered the key mechanism of the formation of sub-grains as well as oriented nucleation, resulting from high contents of vacancy induced by EPT.
研究了电脉冲处理（EPT）对冷轧纯钛形核行为的影响。对试样进行电脉冲处理，然后在650℃下于10分钟内进行退火。利用电子背散射衍射（EBSD）和透射电子显微镜（TEM）技术详细研究了退火过程中再结晶处理初始阶段试样的微观结构演变。结果表明，经电脉冲处理的试样中发生了定向形核。再结晶晶粒以与变形基体晶粒相似的取向形成，并且定向形核起源于经电脉冲处理的试样中<0001>极偏离法线方向（ND20晶粒）约20°的变形晶粒。在ND20晶粒中，棱锥<c + a>位错可被大量激活，而在其他取向晶粒中，激活的位错主要位于棱柱面上。由于亚晶粒的形成离不开棱锥<c + a>位错，因此经电脉冲处理的试样中容易形成定向再结晶晶粒。研究表明，棱锥位错攀移活性的增加被认为是亚晶粒形成以及定向形核的关键机制，这是由电脉冲处理诱导的高空位含量所致。
