Improvement of mechanical properties of Al-Si alloy with effective grain refinement by in-situ integrated Al2.2Ti1B-Mg refiner
Improvement of mechanical properties of Al-Si alloy with effective grain refinement by in-situ integrated Al2.2Ti1B-Mg refiner
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DOI：
10.1016/j.jallcom.2017.03.244
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发表时间：
2017-07
影响因子：
6.2
通讯作者：
Yijie Zhang;S. Ji;Z. Fan
中科院分区：
文献类型：
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作者：
Yijie Zhang;S. Ji;Z. Fan
为了提高铸造Al-Si合金用AlTiB细化剂的有效性和稳定性，研究了原位合成Al2.2Ti1B-Mg中间合金对铸造Al-Si合金的细化作用。实验结果表明，经Al2.2Ti1B-Mg中间合金处理的A356合金获得了细小的等轴晶组织。与常规Al5Ti1B中间合金细化的A356合金的α-Al晶粒度分别为950±1135μm和620±295μm相比，经Al2.2Ti1B-Mg中间合金细化的A356合金的细晶尺寸约为320±550μm。经Al2.2Ti1B-Mg精炼的A356合金的屈服强度、极限抗拉强度和延伸率分别为257±5、313±5和7.8±0.5%，比Al5Ti1B分别提高6%(14/10)、3%(8/6)和13%(1.0%)。A356合金经Al2.2Ti1B-Mg处理后力学性能的改善归因于α-Al相的有效形核。在TiB_2表面形成的MgAl_2O_4层有望减少TiB_2与Al之间的失配，促进α-Al的形核，从而提高细化效果。
In order to improve the effectiveness and stability AlTiB grain refiners for cast Al-Si alloys, the present study investigated the grain refinement of cast Al-Si alloys using an in-situ integrated Al2.2Ti1B-Mg master alloy, which was synthesized through two-step chemical reaction to create TiB2particles and magnesium aluminate (MgAl2O4) phase in the master alloy. Experimental results showed that the fine equiaxed grains were obtained for A356 alloy treated with Al2.2Ti1B-Mg master alloy. In comparison with the α-Al grain size at a level of 950 ± 135 μm and 620 ± 95 μm for A356 alloy without refinement and refined by conventional Al5Ti1B master alloy, the fine grain size of about 320 ± 50 μm could be obtained for A356 alloy refined by Al2.2Ti1B-Mg master alloy. The yield strength, ultimate tensile strength and elongation of the A356 alloy refined by Al2.2Ti1B-Mg was 257±5 MPa, 313±5 MPa and 7.8 ± 0.5% respectively, which was increased by 6% (14 MPa), 3% (8 MPa), and 13% (1.0%) in comparison with that obtained by Al5Ti1B. The improvement of mechanical properties of A356 alloy after treated by Al2.2Ti1B-Mg was attributed to the effective nucleation of α-Al phases. The formation of MgAl2O4layer on the TiB2surface was expected to reduce the misfits between TiB2and Al and promote the nucleation of α-Al, and therefore improve the effectiveness of grain refinement.