Influence of cryogenic treatment time on microstructure and mechnical properties of 3102 H18 alloy

In the paper,the microstructures and the properties of 3102 aluminum foils which are cryogenic treated at different times are investigated.The results show that,after 5min cryogenic treatment,the tensile strength is improved from 233-263MPa and the micro-hardness is obviously enhanced,but there is no obvious change in elongation.With the increase of cryogenic treatment time,the strength and the hardness remain stable,however,the elongation is improved slightly and it is 1.5 times that of originality after 24h cryogenic treatment.TEM and XRD analysis show that second phase precipitates out in the alloy with 5min cryogenic treatment,and further to increase the cryogenic treatment time,the precipitated quantity is finite.With 5h cryogenic treatment,the grains begin to break into much smaller ones.After 24h cryogenic treatment,the grains are fully broken into close grain with the grain size of 0.3-2.5μm.