| As currently the most widely used cast magnesium alloy, AZ91 possess exceptional casting properties, much higher mechanical properties at room temperature, and inferior tenacity, strength of heat, and decay resistance, which limit its further Industrial application. Although rare earth could improve overall properties of AZ91 to a certain extent, coarse needle-shaped rare earth phase restricts the further improvement of its mechanical properties, which there is not scientific research on.In terms of optical microstructure, X-ray diffraction, scan electric microscopy, this topic analyse specifically variety of microstructure, room-temperature and high-temperature strength in RE alloying and the improvement of Sb, and study its mechanism.We find that RE alloying could improve mechanical properties, and grossly exorbitant RE will worsen organization and properties. After composite alloying of Sb in the right amounts, there are many granular portraits of RESb and short rod portraits of Mg3Sb2 in AZ91-xRE.Compared with AZ91-1.0%RE, the microhardness, tensile strength, yield strength, elongation, impact toughness and liquidity of the as-cast AZ91 alloy which is added with 1.0% RE and 1.2% Sb are 3.05%,10.65%,26.51%,14.52%,4.49%,28.13% much higher.The orthogonal action of RE and Sb shows changes in the shape of wave.Moreover, in the respect of high-temperature strength, the steady-state creep stage of AZ91-1.0%RE-1.2%Sb is close to 60 hours, the elongation approximates to 0.53 mm, and the minimum creep rate has a larger reduction than that of AZ91-1.0%RE. During corrosion process, the organizational structures of the composited alloy change greatly and the corrosion resistance obtain a good improvement.Combination of thermodynamics and analysis of cast alloy, we find that Sb alloying improves process of the formation of precipitated phase by augmenting nucleation phase.Dispersion strengthening effects of RESb and Mg3Sb2 of the organization are significant.
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