The material used in the experiment is A356.2 aluminum alloy. The rare earth elements Sc and La are added in the form of Al-2.01% Sc and Al-9.62% La master alloys respectively. Put A356.2 aluminum alloy into a graphite crucible resistance furnace, and the temperature rises to 740 ℃. After the A356.2 aluminum alloy is completely melted, remove the slag, put Si and stir the melt, and then raise the temperature to 790 ℃. Add Al 9.62% La master alloy, stir the melt for 1 min, keep it warm for 15 min, and cool it to 740 ℃. Add Al-1. 98% Sc master alloy to melt, stir the melt, and make the alloy composition uniform. Lower the temperature to 725 ℃. Fill in high-purity nitrogen for refining, After slagging and standing, pour into the cast iron mould preheated to 310 ℃, take out the sample, water quench, and prepare A356.2 (Sc, La) aluminum alloy. See the table for its chemical composition.
In the test, the content of rare earth Sc is 0.38wt%, and the content of rare earth La is 0.14wt%, and a comparative test is carried out. The metallographic structure analysis was carried out on AxioimagerA2m research grade intelligent digital material microscope. The tensile strength and elongation of the alloy were measured by CMT5105 electronic universal testing machine. The Quanta 600 scanning electron microscope and Genesis energy spectrometer were used for microscopic observation and energy spectrum analysis. The alloy phase was analyzed by EMPYREAN X-ray diffractometer.