Papers by Author: Yan Jun Li

Abstract: During casting and homogenisation of aluminium the microstructural fundament for further processing is made. Particle structure (dispersoids and primary particles), grain structure and level of elements in solid solution govern the mechanical and annealing properties of the material. In 3xxx-alloys, Mn in solid solution and Mn-containing dispersoids formed during homogenisation play an important role in controlling the recrystallization behaviour of the material [e.g. 1, 2, 3]. Other elements, such as Si, will have an influence on the formation of dispersoids [4, 5]. Hence, to control the annealing behaviour of the material, it becomes important to control the particle structure. In the present investigation, an AA3103 alloy, and modified versions of this alloy, have been investigated. Various homogenisation treatments have been performed and the resulting material has been studied. Electrical conductivity has been measured and microstructural investigations have been carried out.

Abstract: A simplified numerical model for the solid state phase transformation from Al6(Mn,Fe) to α-Al(Mn,Fe)Si phase in 3xxx alloys has been constructed. In this model, the phase transformation is assumed to be initiated by the heterogeneous nucleation of α-Al(Mn,Fe)Si dispersoids at the interface between Al6(Mn,Fe) particle and matrix and the growth of the α- Al(Mn,Fe)Si phase into the Al6(Mn,Fe) particle is controlled by the diffusion of Si from the matrix. The model has been implemented into a numerical homogenization model. The simulation results show that the implementation of the phase transformation model improves much the prediction results of the homogenization model on the evolution of solid solution level of alloying elements and the volume fraction evolution of dispersoids in 3xxx alloys during homogenization.