Effect of Cryogenic Treatment on the Microstructure and Mechanical Properties of Al-Si Alloy

Some cryogenic treatment experiments were carried out on Al-Si alloy at liquid nitrogen temperature ((-196)) for 72 hours and 120 hours respectively,and the mechanical properties were tested and the microstructures were observed and analyzed.The experimental results show that the strength and hardness of the Al-Si alloy can be enhanced remarkably through cryogenic treatment,moreover,all of the strength,hardness and ductility can be increased at the same time if cryogenic-treated for appropriate time.The primary research indicates that the mechanism of improving the properties of Al-Si alloys through cryogenic treatment is mainly due to producing a lot of tangled dislocations and some dispersion precipitates.