Research On Microstructure And Mechanical Properties Of (AlSiTiCrNiCu)_p/6061Al Composites

Aluminum matrix composites have been widely used in many fields because of their low density and excelent comprehensive properties.However,traditional aluminum matrix composites mostly use ceramic particles as reinfored phase,which will seriously affect the plasticity and toughness of the composite materials and restrict their application as structure materials.In order to change this phenomenon,and to get the composite materiasl with high strength and good plasticity at the same time,the selection of the reinforcing phase must be reconsidered.As a new type of alloy,high entropy aloy has excelent physical and mechanical properties.In addition,high-entropy aloys have the characteristics of metals and unique microstructures,and will have good metal urgical bonding with other metals.It is a very promising kind of reinforcement material.In this work,the AlSiTiCrNiCu low-density high entropy aloy powder obtained by mechanical aloying was used as the reinforcement,with 6061 Al as the matrix.(AlSiTiCrNiCu)p/6061 Al composites are synthesized by spark plasma sintering and hot pressing sintering with the volume fraction of reinforced particles of 0%,3%,and 5%The influence of the volume fraction of high-entropy aloy particles and the process parameters on the microstructure and mechanical properties of(AlSiTiCrNiCu)p/6061 Al composites were investigated.The following results are mainly obtained:The lightweight AlSiTiCrNiCu HEAs with BCC structure are well prepared by mechanical aloying and have excelent homogeneity in composition.There isThe AlSiTiCrNiCu HEAs particles distribute on 6061 Al matrix uniformly and the composite powders are consolidated into highly dense(96 %)bulk specimens by SPS.There are two types of interfaces on(AlSiTiCrNiCu)p/6061 Al composites,which are mechanical IV interface and diffusional interface,respectively.The sintering temperature has a great effect on boundaries between matrix and reinforcement.The interfaces are mainly mechanical interface at low sintering temperature.As the sintering temperature increasing,the boundaries mainly are diffusional interface.The composites have a significant hardness and strength enhancement when adding HEAs and the effects of reinforcement on ductility are smaller than ceramics particulate.When the volume fraction of HEAs is 3%,the(AlSiTiCrNiCu)p/6061 Al composites after T6 dealing show the hardness of 83.2HB,the yield strength of 368.8 MPa,the compression strength of 509.3MPa and compression strain of 6.3%.The higher reinforcement particles contents,the higher hardness and strength of composites,and the composites keep good plasticity.With increasing of sintering temperature,the hardness and yield strength of(AlSiTiCrNiCu)p/6061 Al composites are enhanced,while the compression strength and compression ratio first increase and then become lower.The composites sintered at 520°C have excelent comprehensive mechanical properties.As the volume fraction of high-entropy aloys increases,the thermal conductivity of the composites gradually decreases.