【作者】 黄继武； 尹志民； 李杰； 王涛；

【Author】 Huang Jiwu, Yin Zhimin, Li Jie, Wang Tao( School of Materials Science and Engineering , Central South University, Changsha 410083, China ; Northeast Light Alloy Co. , Ltd. , Harbin 150060, China)

【机构】 中南大学材料科学与工程学院； 东北轻合金有限责任公司；

【摘要】 用硬度和电导率测量、金相和X射线衍射物相分析技术研究了超高强7055铝合金在不同均匀化处理工艺条件下组织和性能的变化规律。实验结果表明,在400℃以下均匀化,合金硬度降低,电导率则升高;400℃以上均匀化,合金的硬度先升而后降,合金的电导率则单调下降。金相和X射线物相分析的结果表明,400℃以下均匀化,半连续激冷铸造得到的过饱和固溶体分解析出平衡相,基体过饱和程度下降导致合金的硬度下降而电导率上升;400℃以上均匀化,一方面,枝晶偏析逐渐消除,另一方面,析出的平衡相又回溶到固溶体基体中,基体过饱和程度增大,合金的硬度增加而电导率则随之下降。均匀化温度愈高,平衡相溶解愈充分,合金的电导率下降愈多。与此同时,合金晶粒粗化,合金的硬度又随之下降。综合分析的结果表明,450℃/24 h是较为理想的均匀化处理工艺。更多还原

【Abstract】 The microstructures and properties of ultra high strength 7055 aluminum alloy at different homog-enization treatment condition were studied bi hardness (HB), electroconductivity (δ) measurement, optical metallography(OM) and XRD analysis. The results show that when homogenization temperature is below 400℃, the hardness of the alloy decreases but electro-conductivity increases; When homogenization temperature is above 400 ℃, the HB of the alloy increases at beginning and then decreases, but the δ value of the alloy decreases. OM and XRD analysis shows that the change of hardness and electroconductivity of the alloy during homogenization is corresponding to the variety of the microstructures. When the alloy is homogenized below 400 ℃, the super saturated solid solution in as-cast alloy decomposed and equilibrium phases,η and S precipitated at beginning, then re-solu-tioned into the matrix again. The degree of supersatu-ration in the matrixes decreases insulted in the hardness decrease and δ value increase. When the alloy is homogenized above 400 ℃, the dentrite segregation is removed gradually. All the same time the equilibrium phases resolve into the solution matrixes, owing to the increase of degree of supersaturation, the hardness of the alloy increases, but the electro conductivity decreases. When the homogenization temperature in-creases further, more equilibrium phases are dissolved and the matrix, and the conductivity of the alloy decreases. To a more extent at the same time, the grain size grows up and hardness of the alloy decreases. Comprehensive analysis shows that the appropriated homogenization treatment processing should be at 450 ℃ for 24 h.更多还原