铝合金中Portevin-Le Chatelier效应的研究进展

Research Progress of the Portevin-Le Chatelier Effect in Aluminum Alloy

铝合金具有高的比强度与耐蚀性,在航空航天及轨道交通领域应用广泛。作为一种常见于铝合金中的塑性不稳定现象,Portevin-Le Chatelier(PLC)效应是一种典型的多尺度效应。该效应在宏观尺度上表现为,在一定温度和应变速率范围内,材料塑性变形呈现锯齿状波动的应力-应变曲线,并在试样表面伴随出现局部变形带;而在微观尺度上,这种现象则涉及位错与溶质原子间的动态交互作用。室温下铝合金形变过程中可能伴随的PLC效应会造成其塑性的降低和表面粗糙化,影响其可成型性及力学服役性能,一定程度上制约了其工程应用。因此,研究铝合金PLC效应的外在表现和内在机理具有重要的理论意义和工业应用价值。主要从类型特点、机理分析、影响因素和发展趋势4个方面对铝合金PLC效应的研究进展进行综述讨论:首先介绍了3种常见的PLC效应类型,重点阐述其分类标准、各自特点以及存在的类型转变;其次从动态应变时效理论的发展出发,描述了现阶段对PLC效应的主要理论解释;进而以温度、应变速率、晶粒尺寸、沉淀相颗粒等为代表,讨论了多种因素对铝合金PLC效应的影响;最后对铝合金PLC效应的研究发展趋势进行了展望。

Due to the high strength-to-weight ratio and excellent corrosion resistance of aluminum alloys,they have been widely used in the aerospace and rail transportation industries.The Portevin-Le Chatelier(PLC)effect,a class of plastic instability frequently observed in aluminum alloys,is a typical multi-scale phenomenon.Macroscopically,the PLC effect manifests itself as the serrated flow on stress-strain curves and highly-localized deformation bands on the sample surface within a certain range of temperature and strain rate.Microscopically,this phenomenon is related to the interactions between dislocations and mobile solute atoms.The PLC effect may occur at room temperature,increasing the surface roughness while decreasing the necking strain in aluminum alloys.The resulted degeneration of material formability and ductility restricts their practical applications to a certain extent.Therefore,a deep insight into the PLC effect in aluminum alloys has important theoretical and industrial meanings.In this paper,the latest research progress of the PLC effect was reviewed from four aspects for aluminum alloys,including characteristics,theoretical explanations,influencing factors,and research tendency.Firstly,three classical types of the PLC effect were introduced,with an emphasis on their classification criteria,basic features,and the transitions between different types.Secondly,the general interpretations of the PLC effect were summarized,with an interest in the historical development of the dynamic strain aging theory.Thirdly,the effects of temperature,strain rate,grain size,and precipitates on the PLC effect of aluminum alloys were discussed in details.Finally,a brief prospect of the PLC effect in aluminum alloys was proposed.