焊后退火Al-Mg界面金属间化合物生长行为

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

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-Al_3Mg_2(靠近铝侧)相和γ-Al_(12)Mg_(17)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-Al_3Mg_2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^(-14)m^2/s增加到3.67×10^(-13)m^2/s.界面IMC层的生长激活能为82.5 kJ/mol.

The paper investigated the microstructure of the friction stir lap welded dissimilar joint between 6061 aluminum alloy and AZ31 B 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-Al_3Mg_2 (near Al side) and γ-Al_(12)Mg_(17) 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) m^2/s.The growth activation energy for the growth of IMC was 82.5 kJ/mol.