Research on Solution and Aging Treatment of Mg-7Zn-3Al Alloy
Effect of solution and aging treatment on the microstructure of Mg-7Zn-3Al alloy is studied by using optical microscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy and quantitative image analysis. The results show that the as-aged microstructure is composed of α-Mg matrix, grain boundary τ (Mg32(Al,Zn)49 ) phase, and fine dispersed τ particles inside the grain. The solution degree has significant effects on the formation, morphology, and size of the grain boundary τ phase. The volume fraction and the size of the undissolved eutectic τ phase decrease with the increase of solution time treated at 325°C. Through sufficient solution treatment, discontinuous eutectic τ phase retains fine strip morphology after aging, in contrast to the microstructure in sample undergone insufficient solution which manifests as-cast feature, while at the same time nano-sized particles precipitate out from the matrix. The precipitates display paralleled short bar, having certain orientation relationship with the matrix.
Young Won Chang, Nack J. Kim and Chong Soo Lee
J. Zhang et al., "Research on Solution and Aging Treatment of Mg-7Zn-3Al Alloy", Materials Science Forum, Vols. 561-565, pp. 247-250, 2007