中文摘要：

研究了不同直流电流密度条件下一种镍基单晶高温合金中γ′相的析出行为．合金经1250℃固溶4h处理后，对其施加不同电流密度且以不同冷却方式进行冷却，考察直流电流对γ′相析出的影响．结果表明，合金在固溶处理后空冷时，随电流密度的增加，γ′相的尺寸和体积分数均增加，面密度减小；在相同的电流密度作用下，随着冷却速率的增加，γ′相尺寸和体积分数减小，面密度显著增加．直流电流产生的电迁移效应和Joule热效应影响γ′相的析出过程，电迁移效应加速原子的扩散，对γ′相析出起促进作用；Joule热效应降低冷却速率，促进γ′相的长大．

英文摘要：

The effects of DC electric current on the precipitation of γ′-phase in a Ni-based single crystal superalloy were studied. Under the action of different current densities the superalloy was cooled at different cooling rates after solution heat treatment at 1250℃ for 4 h. The experiment results show that the size and volume fraction of γ′-phase increase with the increase of current density, while the planar density of γ′-phase decreases at air cooling; under the action of the same current density, the size and volume fraction of γ′-phase decrease and the planar density of γ′-phase increases with the increase of cooling rate. It is considered that the electromigration effect induced by the DC current accelerates the diffusion of atoms during γ′-phase precipitation, which enhances the precipitation of γ′-phase, and the Joule heat effect produced by the DC current reduces the cooling rate, which speeds up the growth of γ′-phase.