Oxide films hinder diffusion and resist external forces, which determines the flame ignition mechanism of magnesium alloys. The effects of the continuity, compactness and mechanical properties of oxide films on the ignition mechanism were analyzed, by investigating the flame ignition behaviors of AZ80 (ZM5), EZ30K (ZM6) and WE43 Mg alloys. The results show that the rupture of the oxide films caused by liquid gravity was the key to causing ignition. According to thermodynamic calculations, compared with Mg, Al cannot be preferentially oxidized; while Nd can be preferentially oxidized through significant enrichment, resulting in a discontinuous NdO inner layer in the ZM6 alloy; in contrast, Y has a strong preferential oxidation ability, which gives the WE43 alloy a continuous YO inner layer and self-healing ability. In addition, the oxide film of the ZM5 alloy is loose and has poor mechanical properties, so it cannot effectively hinder diffusion and resist liquid gravity. Differently, the oxide films of the ZM6 and WE43 alloys are dense and have better mechanical properties, leading to higher ignition temperatures and longer ignition times. In addition, a criterion was proposed to predict the ignition time based on the law of energy conservation, and it was simplified to predict the ignition temperature. The errors between the predicted and measured values are within 11%.

中文翻译：

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基于Al、Nd、Y氧化行为的氧化膜控制镁合金火焰点火机制


氧化膜阻碍扩散并抵抗外力，决定了镁合金的火焰点火机制。通过研究AZ80（ZM5）、EZ30K（ZM6）和WE43镁合金的火焰点火行为，分析了氧化膜的连续性、致密性和力学性能对点火机制的影响。结果表明，液体重力引起的氧化膜破裂是引起着火的关键。根据热力学计算，与Mg相比，Al不能优先被氧化；而Nd可以通过显着富集而被优先氧化，从而在ZM6合金中形成不连续的NdO内层；相比之下，Y具有很强的优先氧化能力，这使得WE43合金具有连续的YO内层和自修复能力。另外，ZM5合金的氧化膜疏松，力学性能较差，不能有效阻碍扩散和抵抗液体重力。不同的是，ZM6和WE43合金的氧化膜致密，具有更好的机械性能，从而导致更高的点火温度和更长的点火时间。此外，基于能量守恒定律提出了点火时间的预测准则，并简化了点火温度的预测。预测值与实测值的误差在11%以内。