Zhu Yan-ping

Effects of Ca addition on the microstructure and mechanical properties of AZ91magnesium alloy

The effects of Ca addition on the microstructure and mechanical properties of AZ91 magnesium alloy have been studied. The results show that the Ca addition can refine the microstructure, reduce the quantity of Mg17Al12 phase, and form new Al2Ca phase in AZ91 magnesium alloy. With the Ca addition, the tensile strength and elongation of AZ91magnesium alloy at ambient temperature are reduced, whereas Ca addition confers elevated temperature strengthening on AZ91 magnesium alloy. The tensile strength at 150°C increases with increasing Ca content. The impact toughness of AZ91magnesium alloy increases, and then declines as the Ca content increases. The tensile and impact fractographs exhibit intergranular fracture features, Ca addition changes the pattern and quantity of tearing ridge, with radial or parallel tearing ridge increasing, tensile strength, elongation and impact toughness reduce.

Influence of beryllium and rare earth additions on ignition-proof magnesium alloys

Abstract A kind of magnesium alloy which has excellent ignition-proof performance and approximate chemical composition with AZ91D alloy was obtained by beryllium and rare earth (RE) addition. A high content of beryllium in magnesium alloy could prevent the ignition of the magnesium, but it also makes the grain coarse and decreases the tensile properties. RE elements were added to refine the grains and improve the tensile strength to the level of AZ91D. On the other hand, casting properties such as fluidity and hot-tearing property were better than those of AZ91D alloy.

Study on the fluidity of AZ91+xRE magnesium alloy

Influence of section thickness, pouring temperature, mould temperature and content of rare earth (RE) element on the fluidity of AZ91 magnesium alloy has been studied through fluidity specimens with different section thickness cast in metal mould. The results show that the relation curve of filling length versus section thickness can be divided into two parts: (i) the filling length in the thin section increases slowly with increasing section thickness, after a critical thickness; and (ii) the filling length in the thick section increases rapidly with increasing section thickness. Elevating the pouring temperature has little influence on the fluidity in the thin section, but increases the filling length in the thick section remarkably. As mould temperature increases, the fluidity in the thin section increases a little, but the fluidity in the thick section rapidly increases. As RE content increases, the fluidity in the thin section changes from increasing to decreasing, and the fluidity in the thick section changes from increasing to decreasing, and to increasing again. Moreover, the critical thickness separating region of thin and thickness section behavior moves to higher values.