| Homogeneous heat treatment can effectively improve the casting magnesium alloy tissue instability,uneven composition and other issues.The research materials of this paper are two kinds of new magnesium alloy Mg-9Al-6Ti-3B2O3 and Mg-6RE-3B2O3 magnesium alloy developed by Bu Leping and others.The effects of heating temperature,holding time,heating rate and cooling rate on the heat treatment of magnesium alloy were studied by single factor method.Then,the casting Mg-9Al-6Ti-3B2O3 alloy and the casting Mg-6RE-3B2O3 alloy were obtained by the orthogonal test method and the observation and analysis by electron microscope and energy dispersive spectrometer and get each of them a better homogenization process.The main research contents and results are as follows:1.A better homogenization process to the casting Mg-9Al-6Ti-3B2O3 alloy is:first heat resistance furnace to 250 ?,and then wrapped with aluminum foil alloy tightly into the furnace,and keep 8?/min Heating rate The resistance furnace to 410 ? after the continuous insulation of 20h,and finally put the alloy in the air flow to room temperature.After the heat treatment the unbalanced second phase of the alloy after homogenization disappears,and a small amount of strengthening phase is precipitated at the grain boundary.The tensile strength and elongation of the alloy were improved before heat treatment,from the previous 180 MPa,7.1%to 230 MPa,11.2%.2.A better homogenization process of Casting Mg-6RE-3B2O3 alloy is:first heat resistance furnace to 250 ?,and then wrapped with aluminum foil alloy tightly into the furnace,keep 8?/min heating rate of Resistance furnaceto 490 ? after 8 hours,and finally put the alloy in the air flow to room temperature.After homogenization,many adjacent grains are combined together,and the second phase of the island-like phase is precipitated at the grain boundary.The tensile strength and elongation of the alloy are improved after heat treatment,respectively,from the previous 170 MPa,6.4%to 220 MPa,11.0%. |
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