Research On The Microstructure And High Temperature Mechanical Properties Of Heat-resistant Aluminum-copper Alloys With High Fe And Si Impurities

With the rapid development of aerospace and transportation fields,the demand for higher performance of heat resistance,light and low-cost aluminum alloys is growing.In this paper,the Al-Cu alloys with high impurity contents of Fe and Si are taken as the research object.The microstructure and high-temperature mechanical properties of the heat-resistant Al-Cu alloys with high impurity contents of Fe and Si are studied by optical microscope,scanning electron microscope,transmission electron microscope,X-ray diffraction analysis,and tensile test etc methods.The results are shown below:1.The effect of different Si contents on the microstructure and mechanical properties of Al-6.5Cu-0.6mn-0.5Fe at room temperature have been studied.It is found that the addition of Si element can promote the transformation of T(Al₂₀Cu₂Mn₃)phases to nano-sized?-Fe(Al₁₅?Fe Mn?₃Cu₂)phases in the matrix,resulting in the coarseness of grains size.And it also can in hibit the transformation of?-Fe(Al₁₅?Fe Mn?₃Cu₂)to?-Fe?A1₇Cu₂?Fe Mn??during heat treatment,increasing the quantity of intergranular Al₂Cu phase.As a result,the mechanical properties of the alloy at room temperature decrease with the increase of Si content in the alloy.However,when the Si content is less than 1.0%,mechanical properties of the alloy decrease slightly at room temperature.2.The effect of different Si contents on the microstructure and high temperature mechanical properties of Al-6.5Cu-0.6Mn-0.5Fe alloy have been studied.It is found that the?-Fe((Al₁₅?Fe Mn?₃?Cu Si?₂)phase with high Si content is an unstable phase in high temperature tensile loading,which will transform into?-Fe?A1₇Cu₂?Fe Mn??.At the same time,Si particles are precipitated.Therefore,the high temperature mechanical properties of the alloy decrease with the increase of Si content in the alloy.But when the Si content is less than 0.5%,high temperature mechanical properties of the alloy decrease slightly.The content of Si in the heat-resistant Al-Cu alloys can be increased to 0.5%,which provides a large space for the recycling of waste aluminum.3.The effect of different Ni content on the microstructure and mechanical properties of Al-6.5Cu-0.6Mn-0.5Fe-0.5Si alloy have been studied.It is found that the addition of Ni element can promote the stability of?-Fe((Al₁₅?Fe Mn?₃?Cu Si?₂)phase and change Al₂Cu on the grain boundary into Al₃Cu Ni phase.As a result,the addition of Ni element in the alloy can improve the mechanical properties of the alloy at both room temperature and high temperature.4.The microstructure and high temperature mechanical properties of Al₃Ti/Al-6.5Cu-1.0Mn-0.5Fe-0.5Si-0.5Ni alloys under different physical fields?ultrasonic vibration field,ultrasonic and mechanical vibration field?were studied.The results show that the distribution of Al₃Ti phase is uniform and the second phase in?-Al matrix can be refined by applying ultrasonic vibration field and mechanical vibration field.Therefore,applying ultrasonic vibration field and mechanical vibration field can improve the high temperature mechanical properties of the alloy.