Microstructure and texture characterization of 7075 Al alloy during the SIMA process

The effect of SIMA process parameters on the crystallographic texture and microstructure of 7075 aluminum alloy was investigated. Specimens of 7075 were subjected to 10-55% uniaxial compression strain at ambient temperature and then semi-solid treatment was carried out at a range of 600 to 620 °C for 5-35 min. The fiber textures of < 110>║CD and < 111 >║CD were dominant textures in compressed samples. The textures were transformed to a randomized texture following the formation of equiaxed and globular grains. Intense segregation of Cu and Si and appreciable depletion of Mg were observed at grain boundaries during soaking time. The grain boundary composition approaches Al-Cu and Al-Si binary eutectics, which facilitates grain boundary melting. Effects of temperature and strain on both the coarsening kinetics of solid particles and the pinning of grain boundary liquid films are also discussed.