Influence of Plastic Deformation on Mechanical Properties and Microstructure of Annealed ZL102 Alloy

Extrusion of the annealed ZL102 alloy has been performed at five extrusion ratios of 15, 30, 45, 60 and 75 in the temperature range from 300 degrees C to 460 degrees C. Microstructures and mechanical properties of ZL102 alloy after homogenization have been investigated through SEM and OM microscopic, and the metallographic and fracture surface structure have been observed. The experimental results show that precipitated phase tends to be more homogeneous with the increase of the extrusion temperature at a certain extrusion ratio. In general, the tensile strength of the alloys increases gradually, but the elongation of the alloys decreases gradually. At 380 degrees C, the eutectic silicon phase presents lamellar morphology with uniform distribution, which makes the curve singularity. Furthermore, with the temperature increasing further, the microstructure of the eutectic silicon is refined gradually. At a certain extrusion temperature, with the increase of extrusion ratio, the grain is refined gradually, and the microstructure of the eutectic silicon grows up gradually with uniform distribution, causing the increase of elongation and decrease of tensile strength of the alloy. The impact toughness shows an upward trend after declining firstly in the overall downward trend. When the extrusion ratio is 15, the impact toughness of the alloys reaches its maximum value 1.7J.cm(-2). Tensile fracture surface of samples has characteristics of the cleavage plane and dimples, therefore the fracture belongs to the mixture fracture of toughness and brittleness.