深冷时效循环处理铝基原位复合材料的显微组织和力学性能

发布时间：2018-04-13 13:05

  本文选题：铝基原位复合材料 + 深冷时效循环处理　； 参考：《中国有色金属学报》2015年05期

【摘要】：采用熔体直接反应法,以工业7055铝合金为基体,利用K2TiF6和K2ZrF6多组元制备Al3(Ti0.5Zr0.5)原位颗粒强化铝基复合材料,再将复合材料经过挤压、固溶时效处理后进行深冷时效循环处理。采用正交实验设计法研究降温速度、处理时间和循环次数对复合材料显微组织和力学性能的影响。采用差示热分析仪对复合材料进行低温热分析,采用SEM和TEM对材料显微组织进行观察。结果表明:材料从液氮温度77 K升温至165 K左右时出现了明显的放热峰,此温度处出现了相变。热计算结果表明该温度下大量析出了S相(Al2CuMg)。深冷处理后复合材料内部细小析出相数量增多,主要组分是η(MgZn2)相和η′(MgZn2′)相;随着降温速度、处理时间和循环次数增加,性质不稳定且硬度高的η′相数量减少,性质稳定硬度较低的η相数量增加。与未冷处理试样相比,深冷时效循环处理后试样的平均抗拉强度提高14.7%,冲击韧性提高10.9%,伸长率提高50%,断裂机制为韧窝型断裂机制。当试样具有高强度、高韧性时,对应的最优冷处理参数为:降温速度v为1℃/min、保温时间t为24 h、循环次数N为1或2。当试样的伸长率最高时,对应的参数为:v为10℃/min、t为36 h、N为1。复合材料强化机制为析出相强化、位错强化和细晶强化等。
[Abstract]:Al3Ti0.5Zr0.5Al matrix composites were prepared by melt direct reaction method using industrial 7055 aluminum alloy as matrix and K2TiF6 and K2ZrF6 multicomponent. After extrusion and solution aging, the composites were treated by cryogenic aging cycle treatment.The effects of cooling rate, treatment time and cycle times on the microstructure and mechanical properties of composites were studied by orthogonal experimental design.The low temperature thermal analysis of the composite was carried out by differential thermal analyzer, and the microstructure of the composite was observed by SEM and TEM.The results show that there is an obvious exothermic peak when the temperature of liquid nitrogen rises from 77 K to 165 K, and the phase transition occurs at this temperature.The thermal calculation results show that a large amount of S phase Al _ 2Cu _ (2) MgO is precipitated at this temperature.After cryogenic treatment, the number of fine precipitated phases in the composites increased, the main components were 畏 -mg-Zn2) and 畏 _ (+) MgZn2) phases, and the number of 畏 'phases with unstable properties and high hardness decreased with the increase of the cooling rate, the treatment time and the cycle times.The number of 畏 phase with low hardness is increased.Compared with untreated specimens, the average tensile strength, impact toughness, elongation and elongation of the specimens after cryogenic aging cycle treatment were increased by 14.7%, 10.9% and 50% respectively. The fracture mechanism was dimple fracture mechanism.When the sample has high strength and toughness, the optimal cooling parameters are as follows: cooling rate v = 1 鈩，

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