焊后退火Al-Mg界面金属间化合物生长行为

研究了6061Al铝合金和AZ31B镁合金的搅拌摩擦搭接焊(FSLW)接头微观组织及焊后热处理过程中接头界面金属间化合物(IMC)生长行为. 结果表明，在接头界面处，金属间化合物层由连续的β-Al3Mg2(靠近铝侧)相和γ-Al12Mg17(靠近镁侧)相组成. IMC层的厚度随着时间延长或者温度的提高而增加，并且β-Al3Mg2相生长快于γ-Al12Mg17相. 整个IMC层的生长厚度与退火时间的平方根成线性关系，其生长受扩散机制影响. 随着温度从300 ℃增加到400 ℃，IMC层生长的扩散系数从2.88×10-14m2/s增加到3.67×10-13m2/s. 界面IMC层的生长激活能为82.5 kJ/mol.

Growth behaviour of Al-Mg intermetallics during post weld annealing treatment

The paper investigated the microstructure of the friction stir lap welded dissimilar joint between 6061 aluminum alloy and AZ31B magnesium alloy and the growth kinetic of intermetallic compounds (IMC) during post weld annealing treatment. The results show that the IMC layer consisted of continuous β-Al3Mg2 (near Al side) and γ-Al12Mg17 phase (near Mg side). The thickness of the IMC layer increased with increasing the annealing time and/or annealing temperature. In addition, the β layer was observed to grow faster than the γ layer. The increase of the IMC layer thickness was found to obey a parabolic relationship with annealing time, which reveals diffusion controlled mechanism during annealing. As the temperature increased from 300 ℃ to 400 ℃, the diffusion coefficient in the IMC layer increased from 2.88×10 14 m2/s to 3.67×10-13 m2/s. The growth activation energy for the growth of IMC was 82.5 kJ/mol.