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采用声发射测试技术,对Al-Si和Al-Cu系合金凝固过程进行监测,证实合金在凝固过程中存在声发射现象,表现为两个声发射信号计数率峰,两个峰的总计数都随着合金中气体含量增加而增高。本文对Al-Si,Al-Cu合金系产生声发射现象的机理进行了探讨,同时,借助其它实验手段证实了声发射信号与合金凝固中气体析出有很好的对应性。第一个计数率峰与气泡在枝晶臂间形核相吻合。第二个计数率峰与凝固末期的枝晶间拉裂现象相对应,可能是氢在枝晶间析出和聚集产生高压氢导致的拉裂。
Acoustic emission testing was used to monitor the solidification process of Al-Si and Al-Cu alloys. It was confirmed that there was acoustic emission during the solidification of the alloy, which was characterized by two AE signal counting rate peaks and two total peak counts With the alloy gas content increased. In this paper, the mechanism of acoustic emission phenomenon in Al-Si and Al-Cu alloys was discussed. At the same time, it was confirmed by other experimental methods that there was a good correspondence between the AE signal and the gas evolution during solidification. The first count rate peak coincides with the nucleation of bubbles in the dendrite arm. The second peak of the count rate corresponds to the phenomenon of delamination between the dendrites at the end of the solidification, which may be due to the hydrogen cracking and delamination caused by high pressure hydrogen during the precipitation and aggregation of hydrogen in the dendrites.