Superplastic behavior of Al-coated Mg alloy sheet
Superplastic behavior of Al-coated Mg alloy sheet
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DOI：
10.1016/j.jallcom.2014.02.099
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发表时间：
2014-07
影响因子：
6.2
通讯作者：
T. Tokunaga;K. Matsuura;M. Ohno
中科院分区：
文献类型：
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作者：
T. Tokunaga;K. Matsuura;M. Ohno
本发明提供一种铝包覆镁合金板，其通过将镁合金坯料与铝板一起热挤压而得到的铝包覆镁合金板进行热锻造而制造。镁合金基体和铝涂层中均存在再结晶细晶。热挤压后，在Al/Mg界面处形成了一层薄的Al 3 Mg 2金属间化合物层。随后的热锻造减小了金属间化合物层的厚度，但在金属间化合物中诱发裂纹。该板材在573 K和1.0 × 10−3s−1的应变速率下表现出550%的大拉伸伸长率。值得注意的是，Al试样的拉伸试验仅表现出40%的伸长率，而Mg合金试样的拉伸试验表现出800%的伸长率。结果表明，镁合金表面Al涂层具有较大的延伸率是由于Al涂层与镁合金基体结合良好所致。金属间化合物层中的裂纹在高温拉伸试验期间消失，并且在伸长试样中没有观察到裂纹，这表明在Al涂覆的Mg合金板的低应变速率热变形期间发生了金属间化合物的生长和裂纹的修复。
An Al-coated Mg alloy sheet is fabricated by hot forging an Al-coated Mg alloy plate produced by hot extrusion of a Mg alloy billet together with an Al plate. The sheet consists of recrystallized fine grains both in the Mg alloy substrate and Al coating layer. A thin intermetallic compound layer of Al3Mg2formed at the Al/Mg interface in the hot-extruded plate. The subsequent hot forging reduces the thickness of the intermetallic layer but induces cracks in the intermetallic compound. This sheet exhibits a large tensile elongation of 550% at 573 K and at a strain rate of 1.0 × 10−3s−1. Notably, a tensile test of an Al specimen exhibited only 40% elongation, while that of a Mg alloy specimen exhibited 800% elongation. It is suggested that the large elongation of Al as the coating layer on the Mg alloy is attributable to the good bonding of the Al coating layer and the Mg alloy substrate. The cracks in the intermetallic layer disappear during the tensile tests at elevated temperatures and no cracks are observed in the elongated specimens, which indicates growth of the intermetallic and reparation of the cracks occurred during the low strain-rate hot deformation of the Al-coated Mg alloy sheet.