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 add ition can refine the microstructure, reduce the quantity of Mg17Al12 phase, and form new Al2Ca phase in AZ91 magnesium alloy. With the Ca addition, th e tensile strength and elongation of AZ91magnesium alloy at ambient tempera ture are reduced, whereas Ca addition confers elevated temperature strength ening on AZ91 magnesium alloy. The tensile strength at 150 degreesC increas es with increasing Ca content. The impact toughness of AZ91magnesium alloy increases, and then declines as the Ca content increases. The tensile and i mpact fractographs exhibit intergranular fracture features, Ca addition cha nges the pattern and quantity of tearing ridge, with radial or parallel tea ring ridge increasing, tensile strength, elongation and impact toughness re duce. (C) 2001 Kluwer Academic Publishers.