【摘要】 研究了不同热处理条件下,时效对Al-Cu合金中锯齿形流动的影响,实验发现,随着自然时效时间的延长,PLC(Portevin-Le Chatelier)效应出现的时间推迟,随着时效的进一步强化(自然时效24 h,或在353 K下保温20 min的人工时效),应力-时间曲线上锯齿幅值减小,出现的频率迅速降低,直至消失。同时,还研究了变形和时效相耦合对锯齿形应力流动的影响,针对所得的实验结果,肯定了基于可动位错和障碍之间的相互作用的动态应变时效微观机制假设,并探讨了出现锯齿形应力流动而无PLC变形带产生的现象。更多还原

【Abstract】 Under different heat-treat conditions, the effect of aging on the serrated flow in Al-Cu alloys is investigated.In the tests, the onset of Portevin-Le Chatelier (PLC) effect is delayed with increasing natural aging time.With further aging (such as natural aging for 24 h, or artificial aging for 20 min at 353 K), the amplitude and frequency of the serrated flow will rapidly decrease, till vanish.The effect of combination of aging and deformation on the serrated flow is also studied.The experimental results confirm the hypothesis about dynamic strain aging mechanism that is based on the interaction between dislocations and obstacles.The phenomenon of serrated flow appearing in the stress-time curves and no PLC deformation band simultaneously existing on the specimen surface is also discussed.更多还原