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    Al-4B中间合金对AZ31镁合金晶粒尺寸和力学性能的影响

    Effect of Al-4B Master Alloy on Grain Size and Mechanical Properties of AZ31 Magnesium Alloy

    • 摘要: 通过KBF4与熔融铝反应制备了Al-4B中间合金,研究了不同质量分数(0%~2.0%)Al-4B中间合金作为孕育剂对AZ31镁合金晶粒尺寸和力学性能的影响。结果表明:Al-4B中间合金由AlB2和α-Al相组成;Al-4B中间合金的添加可以明显细化AZ31镁合金的晶粒,提高晶粒尺寸的均匀性,降低孔隙率,Al-4B中间合金质量分数为1.0%时,晶粒细化效果最明显;随着Al-4B中间合金含量增加,AZ31镁合金的硬度、抗拉强度、屈服强度和断后伸长率均增大,屈服强度与晶粒尺寸符合Hall-Petch关系,AZ31镁合金力学性能的改善主要与AlB2相产生的细晶强化、弥散强化以及铸造组织孔隙率降低有关。

       

      Abstract: Al-4B master alloy was prepared by reaction of KBF4 with molten aluminum. The effects of Al-4B master alloy with different mass fraction (0%-2.0%) as inoculant on grain size and mechanical properties of AZ31 magnesium alloy were studied. The results show that Al-4B master alloy was composed of AlB2 and α-Al phase. The addition of Al-4B master alloy could obviously refine the grain of AZ31 magnesium alloy, improve the uniformity of grain size and reduce the porosity. The grain refinement effect was the most obvious when the mass fraction of Al-4B master alloy was 1.0%. With increasing Al-4B master alloy content, the hardness, tensile strength, yield strength and percentage elongation after fracture of AZ31 magnesium alloy increased. The yield strength and grain size were in accordance with Hall-Petch relation. The improvement of mechanical properties of AZ31 magnesium alloy was mainly related to the fine grain strengthening, dispersion strengthening caused by AlB2 phase and the decrease of porosity of casting microstructure.

       

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