This review article provides overall understanding of stainless, environment-friendly, and nonflammable Mg alloys (SEN alloys) recently developed at the Korea Institute of Materials Science. SEN alloys are produced by adding small amounts of Ca and Y (each <1 wt%) into commercial Mg–Al based alloys, resulting in exceptional ignition and corrosion resistances and impressive mechanical properties. Their main advantages of SEN alloys are as follows. (1) A dense multi-oxide layer of SEN alloys comprising MgO, CaO, and YO impedes the outward dispersion of Mg vapor and the inward penetration of O during oxidation, thereby enhancing the oxidation and ignition resistances. (2) The presence of Ca- and Y-based second-phase particles in SEN alloys can enhance their corrosion resistance because Ca-containing particles prevent the spread of corrosion, and the replacement of Al-containing particles with less noble ones containing Y (e.g., Al–Mn–Y or Al–Y particles) retards corrosion. (3) The addition of minor amounts of Ca and Y renders excellent mechanical properties due to improved strengthening effects. These enhanced properties are attributed to more pronounced dynamic recrystallization and grain refining behaviors caused by the second-phase particles during extrusion. (4) Despite the presence of various types of second-phase particles, the fatigue properties of SEN9 alloys are similar to those of commercial AZ91 alloys. (5) Simultaneous introduction of Ca and Y suppresses the formation of MgAl discontinuous precipitates during aging, leading to the enhanced elongation of aged SEN alloys. (6) Adding mischmetal into the SEN9 alloy leads to a six-fold enhancement in extrudability. Consequently, the studies conducted on SEN alloys demonstrate their excellent ignition and corrosion resistances and mechanical properties, which broaden the industrial applications of Mg alloys by addressing their inherent weaknesses.

中文翻译：

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不锈钢、环保、不易燃镁合金（SEN合金）的化学和机械性能：综述

这篇综述文章全面介绍了韩国材料科学研究所最近开发的不锈钢、环保且不易燃的镁合金（SEN合金）。 SEN 合金是通过在商用镁铝基合金中添加少量的 Ca 和 Y（各 <1 wt%）而生产的，从而具有出色的耐燃性和耐腐蚀性以及令人印象深刻的机械性能。 SEN合金的主要优点如下。 (1)由MgO、CaO和YO组成的SEN合金致密的多重氧化物层阻碍了氧化过程中Mg蒸气的向外扩散和O的向内渗透，从而增强了抗氧化性和抗燃性。 (2) SEN合金中Ca和Y基第二相颗粒的存在可以增强其耐腐蚀性，因为含Ca颗粒可以防止腐蚀蔓延，并且用含Y的不太贵重的颗粒代替含Al颗粒（例如，Al-Mn-Y 或 Al-Y 颗粒）可延缓腐蚀。 (3)添加少量的Ca和Y由于改善的强化效果而呈现优异的机械性能。这些增强的性能归因于挤压过程中第二相颗粒引起的更明显的动态再结晶和晶粒细化行为。 (4)尽管存在各种类型的第二相颗粒，SEN9合金的疲劳性能与商业AZ91合金相似。 (5)同时引入Ca和Y抑制时效过程中MgAl不连续析出物的形成，从而提高时效SEN合金的延伸率。 (6) 在 SEN9 合金中添加混合稀土可使挤压性能提高六倍。因此，对 SEN 合金进行的研究证明了其优异的耐燃性、耐腐蚀性和机械性能，通过解决镁合金固有的弱点，拓宽了镁合金的工业应用。