Thermomechanical processing of AlMgSiCu alloys for high electrical and thermal conductivity applications

Al-Mg-Si合金(如：6101和6201合金)，典型成分为0.6-0.9%Mg和0.5-0.9%Si，由于其高导电性和比强度，通常用于架空输电线路和其他电气工程应用。然而，电导率对合金的添加高度敏感，因为较高的镁和硅含量会增加溶质原子对传导电子的散射，从而显著降低电导率。此外，电导率和导热率成正比关系。常规Al-Mg-Si合金采用固溶热处理、水淬、变形和人工时效等机械加工工艺，可获得良好的导电性和机械强度。在AlMgSi中添加少量的Cu，形成季系AlMgSiCu合金，经热处理后具有优异的机械强度。因此，人们可以探索这种AlMgSiCu合金在电动汽车布线系统和电动汽车电池模块冷却系统中的潜在应用，以实现轻量化战略。然而，目前还没有关于这类AlMgSiCu合金的热机械加工和合金化学对其电导率和导热性能的影响的资料。本研究项目的主要目的是建立对AlMgSiCu合金的合金化学和加工（包括熔化、挤压、热处理）对所得显微组织、导电性和机械性能的影响的基本认识，从而开发用于汽车应用的下一代高导热和高导电性铝合金。加工后的切片将使用光学/电子显微镜和涡流法进行分析，以了解成分和加工条件对微观结构、强度和导电性的影响。

Al-Mg-Si alloys (eg. 6101 and 6201 alloys) with a typical composition of 0.6-0.9%Mg and 0.5-0.9%Si, are commonly used in overhead transmission lines and other electrical engineering applications due to its high electrical conductivity and specific strength. However, the electrical conductivity is highly sensitive to alloying additions because higher magnesium and silicon contents significantly deteriorate electrical conductivity due to increased scattering of conduction electrons by solute atoms. Furthermore, there is a direct proportional relationship between electrical conductivity and thermal conductivity .Themomechanical processing involving solution heat treatment, followed by water quenching, deformation and artificial ageing has been applied to conventional Al-Mg-Si alloy to achieve good electrical conductivity and mechanical strength. Small addition of Cu to AlMgSi to form quaternary AlMgSiCu alloy has led to superior mechanical strength after thermomechanical processing route. Hence, one can explore this AlMgSiCu alloy for potential applications in the wiring systems of electric vehicles and in the cooling systems of electric vehicle battery modules to fulfil the light-weighting strategy. However, there is no information on the effect of thermomechanical processing and alloy chemistry of this type of AlMgSiCu alloy on electrical and thermal conductivity properties. The main aim of this research project is to establish a fundamental understanding of the effect of alloy chemistry and processing of AlMgSiCu alloy involving melting, extrusion, thermomechanical treatment on resultant microstructure, conductivity and mechanical properties, so as to develop the next generation of high thermal and electrical conductivity aluminium alloy for automotive applications. The processed sections will be analysed using a combination of optical/electron microscopies and eddy current method to understand the effect of composition and processing conditions on microstructure, strength and conductivity.