中文摘要：

根据表面扩散控制下物质迁移机制，建立力、电、热和内压共同作用下的有限单元法，详细讨论了多场诱发表面扩散下金属材料内部微裂纹的演化过程．结果表明：对于形态比为β的微裂纹，存在一临界电场值Xc．当X〈Xc时，微裂纹逐渐圆柱化；当X〉Xc时，微裂纹分节为上下或左右两个较小微裂纹．随着内压的增大，微裂纹圆柱化时间增长，而分节时间显著减小，且内压有助于微裂纹分节．对于β≥1的微裂纹，当q≤100MPa时，内压对临界值托的影响较小．

英文摘要：

Based on the theory of surface diffusion, a finite element method is developed to simulate shape evolutions of intragranular microcracks in metal materials due to internal pressure, stress field, elec-tric field and thermal gradient induced surface diffusion. The results show that there is a critical electic field strength value Xc for a given crack aspect ratio β. When X〈Xc, the microcraek will evolve into a cylinder di-rectly. When X〉Xc, the microcrack will be divided into two right-and-left or lower-and-upper microcracks. The cylinderization time of the microcrack increases with the internal pressure increasing,while the split-ting time decreases. Besides, the internal pressure is conducive to the microcrack splitting. Moreover, the in-ternal pressure has little influence on critical value Xc when β≥1 and q≤100 MPa.