Severe plastic deformation by friction stir processing and subsequent heat treatment was carried out on cast magnesium alloys AZ91D and AE42 to obtain ultrafine precipitates size and enhance the toughness. The resultant toughness values were analyzed and correlated with microstructure. Toughness of magnesium alloys AE42 and AZ91D was doubled by friction stir processing followed by heat treatment. Ultrafine precipitates in the order of 0.1 to 0.5 micron were formed by the processing + heat treatment. Networked coarse structure was completely eliminated from cast alloys. Friction stir processing acted as severe plastic deformation and the inbuilt energy and dislocations due to the same was reason for the numerous ultrafine precipitates nucleation during the heat treatment. The precipitates were homogenously distributed in matrix.
Dr. Govindaraj M., Balasubramanian, K., Chackingal, U., and K. Rao, P., “Effect of Severe Plastic Deformation and Heat Treatment on Toughness of Magnesium Alloys”, Procedia Materials Science, vol. 6, pp. 37 - 42, 2014.