【摘要】 研究了碱土元素Ca和Sr对AE42耐热镁合金蠕变性能的影响.试验结果表明,铸态AE42合金中的显微组织由α Mg基体、针状的Al11La3 相和少量粒状的Al2La组成.在 175℃, 70MPa的蠕变条件下,针状的Al11La3 相分解成为Al2La和Mg17Al12,导致AE42合金蠕变性能的急剧下降.在AE42中加入Ca和Sr后,针状的Al11La3 逐渐被Al2Ca相和Al4Sr金属间化合物以及少量Al2La取代,分布在晶界的Al2Ca相和Al4Sr相具有很高的热稳定性,使合金的蠕变性能得到了极大的提高.更多还原

【Abstract】 The effects of alkaline elements Ca and Sr additions on creep resistance of heat resistant magnesium alloy AE42 have been studied. The results show that the as-cast microstructure of AE42 is composed of α-Mg matrix, acicular Al₁₁La₃ phase and small amount of particulate Al₂La phase. The poor creep resistance of AE42 at 175℃ and 70MPa is due to the acicular Al₁₁La₃ phase decomposes to Al₂La and Mg₁₇Al₁₂. The acicular Al₁₁La₃ phases is gradually replaced by Al₂Ca and Al₄Sr intermetallic compound and small amount of Al₂La with Ca and Sr addition into AE42. The Al₂Ca and Al₄Sr intermetallic phases distributing at grain boundaries have very high thermal stability, thus resulting in significant improvement of creep resistance.更多还原