【摘要】 采用XRD、SEM和EDS研究了热处理温度对ATX525镁合金相组成、显微组织和析出相成分的影响,考察了保温时间为24 h条件下,Ca Mg Sn相随温度变化的演化规律。结果表明,合金组织中析出相由热稳定性较高的Mg2(Al,Ca)、Al2Ca和Ca Mg Sn等相组成。其中,Ca Mg Sn相中Sn和Ca含量随处理温度变化而变化,从而使其热稳定性和形貌发生变化。当温度低于500℃时,主要发生Ca Mg Sn溶断和破碎过程,体积分数没有显著变化;当温度为550℃时,Ca Mg Sn相发生溶入基体过程,体积分数减少;然而当处理温度为570~600℃,Ca Mg Sn相出现长大现象。获得细化Ca Mg Sn相貌的热处理温度为500~550℃。合金经过550℃/24 h处理后,经200℃/96 h时效,Ca Mg Sn相以条状和细小的颗粒状析出,与颗粒形貌相比,条状Ca Mg Sn相具有铸态时的形貌特征。更多还原

【Abstract】 The phase constitute,the microstructure and the composition of precipitated phases in ATX525 magnesium alloy were investigated using X-ray diffractometer( XRD),scanning electron microscopy( SEM) and energy dispersive spectrometer( EDS). The emphasis was focused on the morphology evolution of Ca Mg Sn phase after heat treatment at different temperatures for 24 h. The results indicate that the precipitated phases in the alloy are composed of Mg2( Al,Ca),Al2 Ca and Ca Mg Sn with relatively high thermal stability. The content of Sn and Ca elements in Ca Mg Sn phase changes with temperature,which results in the evolution of its thermal stability and morphology. The breaking and smashing process for Ca Mg Sn phase are taken place when the heating temperature is lower than 500 ℃ with almost no change of its volume fractions. While the volume fraction of Ca Mg Sn phase decreases due to its dissolution into the matrix when heating temperature is at 550 ℃. However,the Ca Mg Sn phase starts to grow when the temperature is between 570-600 ℃. Therefore,a fined Ca Mg Sn phase can be obtained during heating at 500-550 ℃. Furthermore,an aging treatment at 200 ℃for 96 h is employed for the alloy after heating at 550 ℃ for 24 h solid solution. The results show that Ca Mg Sn phase with plate and small particle forms can be precipitated from the matrix. Compared to the Ca Mg Sn particle,the plate morphology presents the characteristics of that in the as-cast state.更多还原