Rahman Md Hafijur, Todaro Sarah, Waryoba Daudi, Haque Aman
Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA 16803, USA.
Engineering, Applied Materials, Penn State University, 1 College Place, DuBois, PA 15801, USA.
Materials (Basel). 2024 Jun 29;17(13):3188. doi: 10.3390/ma17133188.
This study investigates the effectiveness of combined thermal and athermal stimuli in mitigating the extremely high-density nature of dislocation networks in the form of low-angle grain boundaries in FeCrAl alloy. Electron wind force, generated from very low duty cycle and high current density pulses, was used as the athermal stimulus. The electron wind force stimulus alone was unable to remove the residual stress (80% low-angle grain boundaries) due to cold rolling to 25% thickness reduction. When the duty cycle was increased to allow average temperature of 100 °C, the specimen could be effectively annealed in 1 min at a current density of 3300 A/mm. In comparison, conventional thermal annealing requires at least 750 °C and 1.5 h. For specimens with 50% thickness reduction (85% low-angle grain boundaries), the electron wind force was again unable to anneal the defects even at 3300 A/mm current density and average temperature of 100 °C. Intriguingly, allowing average concurrent temperature of 200 °C eliminated almost all the low-angle grain boundaries at a current density of 700 A/mm, even lower than that required for the 25% thickness reduced specimens. Comprehensive electron and X-ray diffraction evidence show that alloys with extremely high defect density can be effectively annealed in less than a minute at approximately 200 °C, offering a substantial improvement over conventional high-temperature annealing.
本研究调查了热刺激与非热刺激相结合在减轻FeCrAl合金中以小角度晶界形式存在的位错网络的极高密度特性方面的有效性。由极低占空比和高电流密度脉冲产生的电子风力被用作非热刺激。仅电子风力刺激无法消除因冷轧至厚度减少25%而产生的残余应力（80%为小角度晶界）。当占空比增加以使平均温度达到100°C时，在3300 A/mm的电流密度下，试样可在1分钟内有效退火。相比之下，传统热退火至少需要750°C和1.5小时。对于厚度减少50%（85%为小角度晶界）的试样，即使在3300 A/mm的电流密度和100°C的平均温度下，电子风力也无法消除缺陷。有趣的是，在700 A/mm的电流密度下，允许平均同时温度为200°C几乎消除了所有小角度晶界，甚至低于厚度减少25%的试样所需的温度。全面的电子和X射线衍射证据表明，具有极高缺陷密度的合金在约200°C下不到一分钟即可有效退火，这比传统高温退火有了显著改进。
