Enhancement of mechanical properties in high silicon gravity cast AlSi9Mg alloy refined by Al3Ti3B master alloy
Enhancement of mechanical properties in high silicon gravity cast AlSi9Mg alloy refined by Al3Ti3B master alloy
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DOI：
10.1016/j.msea.2017.06.005
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发表时间：
2017-07
期刊：
影响因子：
6.4
通讯作者：
Xixi Dong;Yijie Zhang;S. Ji
中科院分区：
文献类型：
--
作者：
Xixi Dong;Yijie Zhang;S. Ji
研究了未经晶粒细化的高硅Al9Si0.45Mg合金和经Al 5 Ti 1B和Al 3 Ti 3B中间合金细化的高硅Al9Si0.45Mg合金的显微组织和力学性能。结果表明，未细化和Al 5 Ti 1B细化后的初生α-Al晶粒尺寸分别为1288 ± 361 μm和645 ± 146 μm，而Al 3 Ti 3B细化后的初生α-Al晶粒尺寸明显减小至326 ± 116 μm。经T6热处理后，合金的屈服强度、抗拉强度和伸长率分别为298 ± 2 MPa、350 ± 2 MPa和4.5 ± 0.7%。当晶粒细化剂由Al 5 Ti 1B改为Al 3 Ti 3B时，屈服强度由304 ± 2 MPa提高到311 ± 1 MPa，抗拉强度由357 ± 3 MPa提高到366 ± 1 MPa，延伸率由8.0 ± 1.0%提高到11.1 ± 1.2%，提高了38.8%。热处理合金的屈服强度与晶粒尺寸之间的Hall-Petch关系式为σy= 285.1 + 470.2·d−1/2。结果表明，在α-Al基体中析出的α“相使合金达到峰值强化。在Al 5 Ti 1B中间合金中发现TiB 2和TiAl 3颗粒共存，而在Al 3 Ti 3B中间合金中发现TiB 2和AlB 2颗粒共存。AlB 2粒子的孕育处理使Al 3 Ti 3B下的晶粒得到明显细化。Al 3 Ti 3B细化后合金强度的提高主要是由于初生α-Al晶粒的细化，而塑性的提高主要是由于氧化物和气孔缺陷的减少以及晶粒尺寸的减小。
The microstructure and mechanical properties of high silicon Al9Si0.45Mg alloys without grain refinement and refined by Al5Ti1B and Al3Ti3B master alloys were investigated. The results showed that the primary α–Al grain sizes were 1288 ± 361 µm and 645 ± 146 µm in the non–refined and Al5Ti1B refined alloys respectively, and that was decreased significantly to 326 ± 116 µm in Al3Ti3B refined alloy. After T6 heat treatment, the yield strength, ultimate tensile strength and elongation of the non–refined alloy were 298 ± 2 MPa, 350 ± 2 MPa and 4.5 ± 0.7% separately. When the grain refiner was changed from Al5Ti1B to Al3Ti3B, the yield strength was increased from 304 ± 2 MPa to 311 ± 1 MPa, the ultimate tensile strength was increased from 357 ± 3 MPa to 366 ± 1 MPa, and the elongation was increased significantly by 38.8% from 8.0 ± 1.0% to 11.1 ± 1.2%. The Hall–Petch relation between the yield strength and grain size of the heat–treated alloys was determined asσy= 285.1 + 470.2·d−1/2. It was found that β'' phase was precipitated from the α–Al matrix for the peak strengthening of the heat–treated alloys. TiB2and TiAl3particles were found coexisting in Al5Ti1B master alloy, while TiB2and AlB2particles were verified coexisting in Al3Ti3B master alloy. The inoculation of AlB2particles results in the significant grain refinement under Al3Ti3B. The increase of strength in the Al3Ti3B refined alloy is attributed to the refinement of the primary α–Al grains, while the increase of ductility in the Al3Ti3B refined alloy resulted from the reduced oxides and porosity defects as well as decreased grain size.