EFFECT OF CRYOGENIC TREATMENT ON MICROSTRUCTURE AND MICROHARDNESS OF AL 6061-AL 2 O 3 METAL MATRIX COMPOSITES

Cryogenically treated nonferrous metals will exhibit longer wear and more durability. During the metal-making process, when solidification takes place, some molecules get caught in a random pattern. But molecules do move about at subzero and deep cryogenic temperature slowly. This research is focused on the effect of cryogenic treatment on the microstructure changes and hardness properties of Al 6061 alloy and Al-Al2O3 metal matrix composites (MMCs) at -196 °C for different duration. The execution of cryogenic treatment on both alloy and MMCs changed the distribution of β precipitates. The XRD crystallograms reveals that the cryogenic treatment can change the diffraction peak intensity of some crystal planes in MMCs. The influences of different process parameters on micro-hardness of Al alloy were compared and the results showed that cryogenic treatment could improve hardness of Al/Al2O3 composites.