Ignition-proof performance and mechanism of AZ91D-3Nd-xDy magnesium alloys at high temperatures
This study focused on the synergistic effect of alloying elements neodymium (Nd) and dysprosium (Dy) on the ignition-proof performance of AZ91D alloy. The ignition-proof mechanism of AZ91D-3Nd-xDy (x = 0.5, 1.0, 1.5, 2.0 and 2.5wt.%) alloy was discussed in depth through ignition-proof testing and microstructure observation. The results showed that the AZ91 D-3Nd-2Dy alloy exhibited the highest ignition-point of 893 K, increased by 69 K as compared to the AZ91D alloy. The ignition-proof mechanism of Nd and Dy additions lay in three aspects: (1) the formation of denser oxide film consisting of Dy2o3 and MgO improves the oxidation resistance of the alloy, (2) the great reduction of the low melting-point phase β-Mg17Al12, which leads to the decrease in the oxygen diffusion channels, and (3) the newly formed high melting-point phases (Al2Nd and Al2Dy), which block the oxygen diffusion channels and prevent the chemical reaction of Mg and oxygen.
KeywordsAZ91D Nd Dy ignition-proof high temperature
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