Effects of Al-5Ti-1 B on the structure and hardness of a super high strength aluminum alloy produced by strain-induced melt activation process

In this study the effect of Al-5Ti-1B grain refiner on the structural characteristics and hardness of Al-12Zn-3Mg-2.5Cu aluminum alloy has been investigated. The alloy was produced by modified strain-induced melt activation (SIMA) process. Reheating condition to obtain a fine globular microstructure was optimized. The specimens subjected to deformation ratio of 40% (at 300 degrees C) and various heat treatment times (5-40 min) and temperature (550-620 degrees C) regimes were characterized in this study. Microstructural study was carried out on the alloy by the use of optical and scanning electron microscopy (SEM) in both unrefined and Ti-refined conditions. The results showed that for the desired microstructures of the alloy during SIMA process, the optimum temperature and time are 575 degrees C and 20 min respectively. The hardness test results of the alloy also revealed that T6 heat treatment is more effective in hardness enhancement of all specimens in comparison with SIMA processing. (C) 2011 Elsevier Ltd. All rights reserved.