预变形对Fe-Mn合金层错几率和阻尼性能的影响

EFFECT OF PRE-DEFORMATION ON STACKING FAULT PROBABILITY AND DAMPING CAPACITY OF Fe-Mn ALLOY

探讨了Fe-Mn合金的高阻尼机制并采用G-L位错脱钉模型对其进行描述,同时通过测定层错几率,揭示了预变形(0—10%)对Fe-Mn合金阻尼性能影响的本质.采用倒扭摆测试合金的阻尼性能,SEM和TEM观察显微组织,XRD测定物相体积分数和层错几率.结果表明,Fe-Mn合金的高阻尼性能来源于层错界面上Shockley不全位错的脱钉运动,实验结果很好地符合G-L位错脱钉模型;预变形量小于4%时,预变形处理虽然对合金的ε马氏体量没有太大影响,但明显增加了其层错几率,即Shockley不全位错的数量,合金的阻尼性能随变形量增加逐渐提高;预变形量大于4%时,由于ε马氏体和层错的相互交割,增大了Shockley不全位错的脱钉难度,所以合金的阻尼性能随变形量增加逐渐下降.

Fe-Mn alloys have been widely applied to industrial facilities because of their good mechanical properties, high damping capacity at great strain amplitude and low cost. However, the damping mechanism of Fe-Mn alloys is not fully clear now. In this paper, the high damping mechanism of a Fe-Mn alloy and its effect of pre-deformation on damping capacity were studied by using G-L dislocation model and measuring stacking fault probability. The damping capacity was measured using reversal torsion pendulum. The stacking fault probability and volume fraction of ε-martensite were determined by XRD and the microstructure was observed by SEM and TEM. The results show that the high damping mechanism can be described in terms of the breakaway movement of Shockley partial dislocations on stacking faults. Pre deformation has little effect on the volume fraction of c-martensite, but it increases the stacking fault probability in y-austenite and c martensite, so the damping capacity of Fe-Mn alloy is improved. With pre deformation increasing （greater than 4%）, however, the stacking faults and ε martensite segment each other, so the breakaway movement of Shockley partial dislocations is difficult and the damping capacity of Fe-Mn allov decreases graduallv.