La2O3对镦粗Mo棒的横向组织和塑性的影响

Effects of La2O3 on Transverse Microstructure and Ductility of Upset Mo Bars

摘要:

利用锻造镦粗工艺制备了高横向塑性的纯Mo和Mo-La2O3棒，检测了其在不同温度退火后的横向弯曲性能并观察了其组织结构。结果表明：纯Mo棒经锻造镦粗变形85%后横向具有较好的塑性，延伸率达到了5%；而同状态下的Mo-La2O3棒只有2%。这是因为此状态下纯Mo棒中的位错可动性要好。随着退火温度的升高，纯Mo棒和Mo-La2O3棒的横向塑性都逐渐升高，Mo-La2O3棒的最大横向延伸率大于纯Mo棒(超过10%)。Mo-La2O3棒横向塑性的提高与La2O3粒子钝化微裂纹有关。在退火过程中，镦粗纯Mo棒和Mo-La2O3棒都发生了回复再结晶过程，位错组态变化一致，镦粗过程中产生了大量位错胞，随着退火温度的升高而逐步消失

Abstract:

Pure Mo and Mo-La2O3 bars with high transverse ductility were prepared by forging and upsetting. The microstructure and transverse bending properties of both bars were investigated after different annealing treatments. The results show that the pure Mo bars forged and upset by 85% possess good transverse ductility and the elongation reaches 5%, while that of the forged and upset Mo-La2O3 bars is only 2%. It is because the mobility of dislocations in the Mo bars is better than that of Mo-La2O3 bars in this condition. As the annealing temperature increases, the transverse ductility of the two kinds of bars is improved gradually; particularly the elongation of Mo-La2O3 bars annealed at 1200 oC for 1 h exceeds 10%, higher than that of pure Mo bars. In the upsetting process, many dislocation cells can be observed in the Mo-La2O3 bars, which disappeared little by little as the annealing temperature increased, and still there were a lot of tangled dislocations in the cells which were pinned by the dispersed La2O3 particles. The improvement of the transverse ductility of Mo-La2O3 bars is relative with the interaction between the La2O3 particles and dislocations. Both the Mo bars and Mo-La2O3 bars have recovery recrystallization process, and similar dislocation structure change