MICROSTRUCTURE AND PROPERTIES OF IN SI TU Zn MATRIX COMPOSITESREINFORCED BY Mg₂Si AND Si USING CENTRIFUGAL CASTING

In situ three-layer surface composites of Zn-27Al-9.8Mg-5.2Si and Zn-27Al-6.3Mg-3.7Si alloys wereobtained by using preheated metal mould cent rifugal casting1 The surface composites possess the microst ructureaccumulating lot s of blocky primary Mg₂Si and a small amount of blocky primary Si in the inner layer, accumulatingprimary Mg₂Si and primary Si in the outer layer, and without primary Mg₂Si and primary Si in the middle layer1 Butonly single layer material without primary Mg₂Si and primary Si was obtained in cent rifugally cast Zn-27Al-3.2Mg-1.8Si alloy. Microst ructures of cent rifugally cast Zn-27Al-Mg₂Si alloys were investigated, The hardness, wearability and f racture mode of the composites were also analysed, The result s show that the hardness and wear resistanceof the composites depend mainly on the dist ribution of the primary Mg₂Si and primary Si along the radial direction1The inner layer of the composite shows the highest hardness and best wear resistance1 The f racture mode of thecomposite is primarily brittle1 The middle layer of the composite exhibit s more deformation than the inner layer during the f racture1