The Study On The Al-Ca Alloy And Its Microstructure And Performance

Ca is light weight element with rich source. Al-Ca alloy has potentials to be heat resistantalloy because of the high eutectic temperature, and this alloy should have a brilliant future.This thesis mainly studies the effects of different Ca contents on binary Al-Ca alloy, andalso the effect of other alloying elements and heat treatment process on eutectic Al-Ca alloy.OM, XRD, SEM-EDS, presses machine, universal tensile machine and other equipment wereused to study the microstructure, phase composition and mechanical properties of each alloy.The results show that: with the increases of Ca, the content of eutectic increases; when Careached8%the microstructure was just consist of eutectic; when Ca up to11%, the primaryAl4Ca appeared. After heat treatment at550℃and580℃for different time, the eutectic phaseof Al-8Ca trans into particles, the longer treatment time and the higher the temperature, thegreater the size the fewer number of the eutectic particles, and also the more rounded shape.The samples for mechanical testing was extruded after heat treatment for12h at550℃, turnsout the tensile strength is163.3MPa, yield strength is70.7MPa and elongation is4.5%.With6%-10%Mg added, Mg exists as solid solution mainly. The eutectic phase of theAl-7Ca-6Mg alloy also takes a particle transition, the changing trends consistent with Al-8Caalloy. The samples for mechanical testing was extruded after heat treatment for12h at520℃,turns out the tensile strength is253MPa, yield strength is155MPa and elongation is2.3%;The microstructure barely has no change after added0.6%Si. When the additions of Si up to1.8%and3%, the Al2CaSi2phase appeared, and the more Si content, the more and biggerAl2CaSi2phase. The eutectic phase take a particle transition after heat treatment, but theAl2CaSi2phase take no change; After10%-30%added to Al-8Ca alloy, the ternary Zn-richphase appeared, after heat treatment at520℃, eutectic phase particle transition, Zn-rich phasedid not change.