【摘要】 研究了Al3Ti4B中间合金对 Mg 7Al 0.4Zn 0.2Mn合金的显微组织、力学性能及耐腐蚀性能的影响。结果表明: 当Al3Ti4B加入量小于0.3%(质量分数)时, 合金的平均晶粒尺寸显著减小; 当 Al3Ti4B加入量为0.3%时, 合金组织显著细化, 平均晶粒尺寸由未变质合金的 135μm细化到 30μm, 合金拉伸力学性能和耐腐蚀性能最好; 当加入量超过0.3%时, 晶粒粗化; 具有密排六方结构的高熔点化合物 TiB2 (θm =2 980 ℃)和 AlB2(θm=980℃)均可作为α Mg的异质核心, 大量异质结晶核心的存在是导致α Mg晶粒细化的主要原因。更多还原

【Abstract】 The effects of Al3Ti4B master alloy on microstructure, mechanical and corrosion resisting properties of Mg-7Al-0.4Zn-0.2Mn alloys were studied. The results show that the average grain size of alloy decreases when the addition of Al3Ti4B is less than 0.3%（mass fraction）. The microstructure is refined remarkably when adding 0.3% Al3Ti4B, the average grain size decreases from 135 to 30μm. When the Al3Ti4B addition is more than 0.3%, the grain size increases with the increase of Al3Ti4B. The mechanical properties and corrosion resisting properties of alloys with 0.3%Al3Ti4B are the best. High melting point compounds （TiB₂ and AlB₂） with hexagonal closed-packed（HCP） crystal structure can serve as the nucleating sites of α-Mg during solidification, and heterogeneous nucleation is the main reason of the grain refinement of α-Mg grains.更多还原