锯齿形塑性失稳的多尺度关联实验与机理研究

项目名称： 锯齿形塑性失稳的多尺度关联实验与机理研究

项目编号： No.10872189

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 轻工业、手工业

项目作者： 张青川

作者单位： 中国科学技术大学

项目金额： 55万元

中文摘要： PLC效应是一种在工业合金材料中常见的塑性失稳现象。对其深层机理的研究，力求解决在汽车工业航空工业等方面中合金材料的冶炼成材等实际应用问题，是国际上合金材料研究的一个热点。在本基金的支持下，对原有实验平台进行了维护和改进，并建立了新型微观实验观测平台，对多种典型铝合金材料中不同实验条件下的PLC效应从多个方面进行了研究。获得了随着应变率、温度、热处理方式以及试件尺寸改变，应力跌幅、周期以及临界应变等的演化规律；分析了析出相对PLC效应的影响方式，如对临界应变的影响，对溶质原子扩散方式的影响等；结合临界应变之前的应力包络线水平和锯齿方向，探讨了两种临界行为的深层机理及其依赖条件以及临界应变前夕的微观状态；借助红外热成像技术，研究了合金发生塑性不稳定性时的温度场演化情况；建立了"应力-应变-温度"耦合的宏观唯象模型和反映在溶质原子作用下位错运动的微观模型，且模拟结果与实验吻合。同时与国家需求紧密结合，开启了航空发动机涡轮盘材料的镍基合金中PLC效应的研究，取得了初步的成果，为下一步更深入更全面的研究打下基础。部分结果已在Acta Materialia等国内外核心期刊上发表。

中文关键词： 锯齿形屈服；塑形失稳；Portevin-Le Chatelier 效应；动态应变时效；多尺度

英文摘要： As one of plastic instabilities, the Portevin-Le Chatelier (PLC) effect, which is exhibited in many industrial alloys, is a subject of current research interest due to its complex nature and the implications it has in alloy forming processes, e.g. in the automotive industry. With the support of this Funding, the original experimental platform was maintained and improved, and a new experimental platform for microscopic observation was established. By experimental investigations of the PLC effect in several types of Al alloy, the features of the serration amplitude, the serration period and the critical strain at different conditions, including different strain rates, different temperatures, different heat treatments and different sample sizes, were obtained. The influences of precipitation on the PLC effect, especially on the critical strain and the solute diffusion, were revealed. The mechanisms of two critical behaviors were presented relation with the stress envelope curves before the critical strain and the serration directions. The temperature evolution of plastic instabilities in alloys was studied by infrared pyrometry. A macroscopic phenomenological model linked to "stress - strain - temperature" coupling and a microscopic model based on dislocation dynamics were respectively proposed well consistent with experiment. Furthermore, Ni base alloys, which are developed for aircraft engines and industrial gas turbine applications, attracted our attention. The preliminary investigation of PLC effect in Ni base alloys was performed, and more studies will be conducted in the next stage.

英文关键词： Serrated yielding; plastic instability; Portevin-Le Chatelier effect; dynamic strain aging; muti-scale