均匀化工艺对3104铝合金中弥散相分布的影响

Influence of homogenization process on dispersoids distribution in 3104 aluminum alloy

利用光学显微镜和电导率测试仪对3104铝合金不同均匀化条件下的弥散相析出情况进行研究。结果表明,3104铝合金铸锭中只有存在少量Al_(12)Mn_3Si弥散相,均匀化后基体中析出大量Al_(12)Mn_3Si弥散相,呈点状或短棒状,合金电导率升高。随时均匀化温度升高,弥散相发生粗化和回溶,密度减小,尺寸增大,并且合金电导率逐渐降低。因此,经600℃×10 h均匀化弥散相的密度最低,尺寸最大,为400~500 nm。均匀化升温降温速率对弥散相析出有影响,均匀化升温速率减慢,弥散相数量增加,尺寸减小;均匀化冷却速率增加,数量减少,尺寸略有减小;而样品重新在500℃保温2 h后,弥散相数量明显增加,电导率升高,但相互之间差别不大。因此,3104铝合金铸锭在较高温度下(580℃以上)保温较长时间,有利于获得合理的弥散相粒子分布。

The dispersoids distribution of 3104 aluminum alloy under different homogenization processing was investigated by means of optical microscope and electric conductivity test. The results show that there are very few Al12Mn3Si dispersoids in 3104 ingot; after homogenization treatment,lots of Al12Mn3Si dispersoids precipitate as point-like or short rod-like structure,and the electric conductivity of the 3104 alloy increases. With increasing the homogenization temperature,dispersoids become coarse and re-dissolved into the matrix,so the density of the dispersoids decreases,the size increases and the electric conductivity of the alloy decreases. After homogenization at 600℃ for 10 h,the density of the dispersoids is the lowest but the size is the largest,which is about 400-500 nm. Besides,the heating and cooling rates of homogenization have an effect on the dispersoids precipitation. When the heating rate is lower,the dispersoid amount increases but the size decreases; when cooling rate is higher,the dispersoid amount reduces and the size diminishes slightly. While the samples with different cooling rates are reheated at 500 ℃ for 2 h,the disperoids amount increases obviously and the conductivity increases,but the dispersoids distribution is almost the same among different samples. Therefore,the 3104 alloy ingot is homogenized at higher temperature（ 580 ℃） for a long time,benificial to obtain proper dispersoids distribution.