Abstract

The combined addition of small amounts of Ca and Y to Mg–Al–Zn alloys has recently been found to greatly improve the ignition resistance, corrosion resistance, and mechanical properties of these alloys. However, Mg–Al–Zn–Ca–Y alloys with high Al content show poor extrudability, which is an obstacle to their use as extruded components in industrial applications. This study aims to improve the extrudability of a Mg–Al–Zn–Ca–Y alloy through the addition of a small amount of mischmetal (MM). To this end, a trace amount (0.5 wt%) of Ce-rich MM is added to a Mg–9Al–0.8Zn–0.9Ca–0.6Y (AZXW9110) alloy. MM addition leads to significant grain refinement of the homogenized billet, from 326 to 180 μm. When the MM-added alloy is extruded into a sheet at 350 °C with an extrusion ratio of 22.9, the maximum ram speed at which it is extrudable without the occurrence of hot cracking is 12 mm/s, substantially higher than the 2 mm/s possible without MM addition. The Ce and La atoms decomposed from the MM are dissolved in the Mg₁₇Al₁₂, Al₈Mn₄Y, Al₂Ca, and Al₂Y phases, apparently leading to an increase in the thermal stability of the phases and, consequently, to an improvement in the AZXW9110 alloy’s extrudability. At ram speeds above 2 mm/s, many small-sized cracks form at the edges of the extruded AZXW9110–0.5MM sheets. As the ram speed increases up to 6 mm/s, the number density of edge cracks gradually increases while their average spacing decreases, but beyond 6 mm/s both remain almost unchanged.

Graphic Abstract

中文翻译：

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通过添加其他金属元素显着改善Mg-9Al-0.8Zn-0.9Ca-0.6Y合金的可挤压性

摘要

最近发现，向Mg-Al-Zn合金中添加少量的Ca和Y可以大大改善这些合金的耐燃性，耐蚀性和机械性能。但是，铝含量高的Mg-Al-Zn-Ca-Y合金的可挤压性较差，这阻碍了它们在工业应用中用作挤压组件。这项研究旨在通过添加少量的混合稀土（MM）来提高Mg-Al-Zn-Ca-Y合金的可挤压性。为此，在Mg-9Al-0.8Zn-0.9Ca-0.6Y（AZXW9110）合金中添加了痕量（0.5 wt％）的富Ce MM。MM的添加导致均质坯料的显着晶粒细化，从326到180μm。当添加MM的合金在350°C下以22.9的挤出比挤出成片时，在不发生热裂的情况下可挤出的最大冲头速度为12 mm / s，大大高于不添加MM时的2 mm / s。从MM分解的Ce和La原子溶解在Mg中₁₇ Al ₁₂，Al ₈ Mn ₄ Y，Al ₂ Ca和Al ₂ Y相明显地导致相的热稳定性的提高，并因此改善了AZXW9110合金的可挤压性。当冲压速度超过2 mm / s时，在挤压的AZXW9110–0.5MM板材的边缘会形成许多小尺寸的裂纹。当冲头速度增加到6 mm / s时，边缘裂纹的数量密度逐渐增加，而平均间距减小，但超过6 mm / s时，两者几乎保持不变。

图形摘要